At existing dam crest elevation.........         1,044.3             2.0             4.1            60.1             8.4            54.3             507
At mean annual flow of 2,290 cfs........           1,046             2.1             4.2            67.1             9.1            56.0             613
During proposed low-flow project                 1,048.3             2.2             4.8            76.6            10.1            58.3             775
 operations.............................
During spill periods....................         1,050.3             2.3             4.9            88.3            10.6            60.3             938
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Most of the bed-surface substrate is medium sand, with a typical
(median) diameter of 0.4 millimeter (mm); gravel is present at the
upstream end of the reservoir near Shanker's Bend and at depth within
the accumulated sediment. The volume of stored sediment is estimated to
be around 2.4 million cubic yards.
    Groundwater in this sub-basin is primarily supplied from glacial
and alluvial deposits in the lower valley areas. The Similkameen River
once flowed southward through the valley now occupied by Palmer Lake
and Sinlahekin Creek. During the last glaciation, the river was
rerouted through several temporary channels until it finally settled
into its current channel as the glacier retreated. Glacial and alluvial
deposits in the original channel and the temporary channels are several
hundred feet thick with moderate to high yield aquifers. The alluvial
and glacial deposits are composed largely of fine sand, silt, and clay,
with some thin lenses of coarse sand and gravel. Permeability and
yields can be quite high.
    In places where there is a lack of glacial or alluvial deposits,
groundwater is scarce. Subsurface rock consists of metamorphic,
granitic, and consolidated sedimentary rock with low permeability and
porosity.
    During low flow periods, very little flow is added to the river
between the USGS Nighthawk gage (RM 15.8) and the Washington DOE flow
gage at RM 5.0, indicating that groundwater discharge is not a
significant contributor to flow in the lower Similkameen River. The
City of Oroville withdraws its municipal water supply from a well field
located at the confluence of the Similkameen and Okanogan rivers. The
wells are considered to be in continuity with the Similkameen River.
Groundwater would not be affected by the project regardless of its
location relative to the river or degree of continuity because the
project would operate in a run-of-river mode and would not affect flows
or recharge.

Water Quality

    This section describes existing water quality in the lower
Similkameen River and focuses on water quality characteristics that
could be influenced by project construction and operation: Temperature,
DO concentration, total dissolved gas concentration, and contaminants
associated with river sediments.

Water Temperature

    Water temperatures in the Similkameen River upstream of the project
can exceed freshwater aquatic life criteria during the summer months,
and water temperatures generally increase from upstream to downstream.
Okanogan PUD conducted water temperature monitoring in the project area
from late spring through early fall of 2006 to characterize potential
project effects on the water temperature regime. The monitoring study
was designed to measure changes in water temperatures in the
Similkameen River as it flowed through the project area.
    One of the designated uses for the Similkameen River is salmonid
spawning, rearing, and migration. The aquatic life maximum water
temperature criterion set by Washington DOE to protect this use is 17.5
degrees Celsius ([deg]C), measured by the 7-day average of the daily
maximum temperatures (7-DADMax). When a water body's temperature is
warmer than the criterion and that condition is due to natural
conditions, human actions (considered cumulatively) may not cause the
7-DADMax temperature of that water body to increase more than 0.3
[deg]C. In applying this standard to hydroelectric projects, Washington
DOE has interpreted natural conditions to be

the water temperature regime before construction of any dams or other
human influences.
    Washington DOE has identified the Similkameen River below Enloe dam
as a water body requiring special protection for salmonid spawning and
incubation (Okanogan PUD, 2008a). This special criterion identifies a
maximum 7-DADMax temperature of 13 [deg]C at the initiation of spawning
for salmon and at fry emergence for salmon and trout. A maximum 0.3
[deg]C increase also applies to the seasonal criteria for spawning and
incubation. This requirement is applied to the Similkameen River from
February 15 through June 15.
    The 2006 monitoring results showed that the Similkameen River
exceeded the 17.5 [deg]C criterion both upstream and downstream from
Enloe dam from late June through mid-September, with additional
exceedances in late-September (figure 2). The highest temperature of
26.9 [deg]C was recorded both at China Rock (RM 12.2) upstream from the
project site, and at the bridge in Oroville (RM 5.3) downstream from
the project site.
BILLING CODE 6717-01-P
[GRAPHIC] [TIFF OMITTED] TN17MY11.001

    Comparisons of 7-DADMax temperatures at different monitoring
stations indicate that water temperatures did not increase through the
project area by more than 0.3 [deg]C at any time during the 2006
monitoring season, and all stations showed a similar trend in
temperatures. The 7-DADMax temperatures decreased after August 4,
although remained above the 17.5 [deg]C criterion for most of the
remainder of the monitoring period. Figure 3 plots the 7-DADMax
temperatures at the upper end of the reservoir (RM 10.3) and the lower
end of reservoir (RM 9.1).

[GRAPHIC] [TIFF OMITTED] TN17MY11.002

BILLING CODE 6717-01-C

Dissolved Oxygen

    The Water Quality Standards for Surface Waters for Washington state
that the 1-day minimum DO concentration for salmonid spawning, rearing,
and migration is 8.0 milligram per liter (mg/L) (Chapter 173-201A
Washington Administrative Code). When a water body's DO concentration
is lower that this criterion and that condition is due to natural
conditions, human actions considered cumulatively may not cause the
concentration to decrease more than 0.2 mg/L.
    Okanogan PUD measured DO profiles on September 14 and 15, 2006, in
the vicinity of Enloe dam. All measurements were above the 8.0 mg/L
minimum water quality standard. As expected, the DO concentrations were
higher where colder water was encountered in the morning hours below
the dam and at China Rock upstream of the reservoir. Warmer water and
lower DO concentrations were measured in the afternoon hours in the
reservoir pool above the dam.

Total Dissolved Gases

    The Water Quality Standard for Surface Waters for Washington State
requires that TDG shall not exceed 110 percent of saturation at any
point of sample collection (Chapter 173-201A Washington Administrative
Code). The TDG criteria contained in the standards do not apply when
the stream exceeds the 7-day, 10-year frequency flood. The standards
provide allowances for the criteria to be adjusted to aid fish passage
over hydroelectric dams when consistent with a Washington DOE approved
gas abatement plan. However, this allowance does not apply to the Enloe
Project because it would not provide spill to aid fish passage.
    TDG concentrations measured between May 26 and 30, 2006, were below
the 110 percent saturation water quality criterion in the lower
reservoir (RM 9.1) and between Enloe dam and the falls (RM 8.9), but
exceeded the criterion below the falls (RM 8.8) and below the railroad
trestle at the mouth of the canyon downstream from the project area (RM
6.7). Flows ranged between 10,700 cfs at Nighthawk and 12,100 cfs at
Oroville on May 26, 2006, to 8,780 cfs at Nighthawk and 9,640 cfs at
Oroville on May 30, 2006. TDG levels increased by 3 to 7 percent of
saturation after flowing over Enloe dam but remained below the water
quality criterion, with mean hourly TDG levels ranging from 106.1 to
108.7 percent of saturation between the dam and the falls.
    TDG increased substantially after flowing over the falls,
increasing by an additional 12 to 14 percent of saturation. Downstream
of the falls, mean TDG levels ranged from 118.5 to 120.7 percent of
saturation. This TDG increase below the falls is due to the additional
turbulence caused by the falls and the plunging flow into a deep pool
where the increased pressure causes bubbles to dissolve. Near the
railroad trestle located about 2.2 miles downstream of the falls, the
mean TDG saturation was slightly lower (115.3 to 116.2 percent of
saturation), but still remained above the criterion. Table 5 provides
the results of Okanogan PUD's TDG sampling.
    A generalized longitudinal profile adapted from a 1934 USGS survey
indicates that the river drops 46 vertical feet in the 1.6-mile reach
upstream from the dam. This steep gradient suggests that historically
turbulent flows in the reservoir reach before impoundment likely
created aeration and may have contributed to increased TDG saturation
above the 110 percent criterion during high flows. Thus, TDG saturation
above 110 percent was likely a naturally occurring condition below the
falls before the dam was built.

Contaminated Sediments

    Contamination from historical mining operations in the Similkameen
River watershed has resulted in arsenic concentrations exceeding water
quality criteria in samples from Chopaka Bridge in British Columbia (RM
36.1) and Oroville, Washington (RM 5.0) (Peterschmidt and Edmond, 2004;
Johnson, 2002). Washington DOE has completed a total maximum daily load
(TMDL) evaluation and prepared a draft plan to address the arsenic
contamination. The loading capacity for the river was set equal to the
natural background concentration of arsenic (i.e., 0.4 to 0.6 microgram
per liter total recoverable arsenic), because arsenic levels naturally
exceed water quality criteria. The greatest amount of arsenic loading
identified by the TMDL evaluation was caused by resuspension of
sediments in the vicinity of Palmer Creek at RM 20, approximately 10
miles upstream from the project area.

            Table 5--Summary of Total Dissolved Gas Measurements Near Enloe Dam From May 26-30, 2006
                                          [Source: Okanogan PUD, 2008a]
----------------------------------------------------------------------------------------------------------------
                                                              One-hour mean TDG saturation  (percent)
                Time and location                ---------------------------------------------------------------
                                                   May 26 and 27      May 28          May 29          May 30
----------------------------------------------------------------------------------------------------------------
a.m.:
    Lower reservoir.............................           103.4           101.9           102.0           101.1
    Between dam and the falls...................           107.6  ..............           106.2           106.8
    Below the falls.............................           129.7           119.6           118.9           118.5
    Below railroad trestle......................           116.2           115.9           115.6           115.3
p.m.:
    Lower reservoir.............................           102.0           103.3           103.3           102.5
    Between dam and the falls...................           108.7  ..............           106.1           106.8
    Below the falls.............................           120.7           120.6           120.0           119.4
    Below railroad trestle......................           116.2           116.1           115.8           116.0
----------------------------------------------------------------------------------------------------------------

    An analysis of shallow sediment core samples for trace metals,
performed for the Colville, confirmed arsenic contamination in the
Similkameen River and Palmer Creek upstream from Nighthawk, Washington.
Copper also exceeded a Colville sediment quality standard in several
samples, and cadmium exceeded the standard in one sample.
    There are no established state regulatory criteria for chemical
contaminants in freshwater sediments; however, several sediment quality
values have been used to indicate potential toxic effects to aquatic
life. The current Colville Tribal Code contains sediment cleanup levels
both for the protection of human health and for the protection of
sediment-dwelling organisms. The Colville adopted cleanup screening
levels for eight metals, including arsenic, cadmium, and copper.
Washington DOE also set non-regulatory sediment quality values and
cleanup screening levels for freshwater sediment (Michelson, 2003, in
Okanogan PUD, 2008a). Okanogan PUD collected sediment samples in 2007
that were analyzed for pesticides, arsenic, cadmium, and copper. The
sample results, along with the Colville criteria and Washington DOE
non-regulatory sediment quality values are presented for comparison in
table 6.

                                         Table 6--Summary of Preliminary Enloe Dam Sediment Trace Metals Results
                                                   [Source: Okanogan PUD, 2008a, as modified by staff]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Milligrams per kilogram (mg/kg)
             PMX sample ID                River mile           ARI sample ID                  Depth (feet)        --------------------------------------
                                             (RM)                                                                    Arsenic      Cadmium       Copper
--------------------------------------------------------------------------------------------------------------------------------------------------------
Shallow Core Samples:
--------------------------------------------------------------------------------------------------------------------------------------------------------
    EDSG01.............................         10.6  07-16068-LK08A.................  0 to 1....................         15.7     \a\ 0.3U         22.3
    EDSG02.............................           10  07-16069-LK08B.................  0 to 1....................         23.5         0.3U         33.3
--------------------------------------------------------------------------------------------------------------------------------------------------------
VanVeen Grab Samples:
--------------------------------------------------------------------------------------------------------------------------------------------------------
    EDSG03.............................          9.4  07-16070-LK08C.................  0 to 0.5..................         11.2          0.2         18.4
    EDSG05.............................          9.0  07-16071-LK08D.................  0 to 0.5..................         20.4         0.3U         27.9
    EDSG06.............................          9.0  07-16072-LK08E.................  0 to 0.5..................         10.0         0.3U         17.1
    EDSG08 \b\.........................          9.0  07-16073-LK08F.................  0 to 0.5..................          9.2         0.3U         17.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Freeze Core Samples:
--------------------------------------------------------------------------------------------------------------------------------------------------------
    EDSC04-0-4.........................          9.0  07-16099-LK13A.................  0.0 to 5.0................          8.8         0.2U         16.3
    EDSC04-4-8.........................          9.0  07-16100-LK13B.................  5.0 to 6.6................         29.3          0.4         47.5
    EDSC04-8-12........................          9.0  07-16101-LK13C.................  6.6 to 8.0................         10.3         0.2U         16.2
    EDSC08-0-4 \c\.....................          9.0  07-16102-LK13D.................  0.0 to 5.0................          7.0         0.2U         13.6
    EDSC08-8-12 \d\....................          9.0  07-16103-LK13E.................  6.6 to 8.0................          8.6         0.2U         16.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Surface Grab Samples Below Enloe Dam (RM 8.9):
--------------------------------------------------------------------------------------------------------------------------------------------------------

    07-16081-LK11A.....................          8.7  SR-1...........................  0.0 to 0.1................         24.8          0.3         31.8
    07-16082-LK11B.....................          8.2  SR-2...........................  0.0 to 0.1................          9.3         0.3U         16.0
    07-16083-LK11C.....................          7.6  SR-3...........................  0.0 to 0.1................         10.6         0.2U         15.9
    07-16088-LK11H \e\.................          7.6  SR-8...........................  0.0 to 0.1................         10.4         0.3U         14.4
    07-16084-LK11D.....................          6.8  SR-4...........................  0.0 to 0.1................          9.1         0.3U         15.1
    07-16085-LK11E.....................          6.6  SR-5...........................  0.0 to 0.1................          8.2         0.3U         12.8
    07-16086-LK11F.....................          6.1  SR-6...........................  0.0 to 0.1................          9.5         0.3U         15.1
    07-16087-LK11G.....................          5.7  SR-7...........................  0.0 to 0.1................         13.1         0.3U         17.3
--------------------------------------------------------------------------------------------------------------------------------------------------------
Freshwater Sediment Quality Values:
--------------------------------------------------------------------------------------------------------------------------------------------------------
    Sediment Quality Standard \f\......  ...........  ...............................  ..........................           20          0.6           80
    Cleanup Screening Level \f\........  ...........  ...............................  ..........................           51            1          830
    Cleanup Screening Level \g\........  ...........  ...............................  ..........................         9.79         0.99         31.6
    Probable Effect Concentration \h\..  ...........  ...............................  ..........................           33         4.98          149
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
\a\ Results with ``U'' were not detected in the sample at the accompanying detection limit.
\b\ Duplicate of EDSG06.
\c\ Duplicate of EDSC04-0-4.
\d\ Duplicate of EDSC04-8-12.
\e\ Duplicate of SR-3.
\f\ Michelsen, 2003.
\g\ Colville, 2003.
\h\ MacDonald et al., 2000.

    Cadmium was detected in 3 of 15 samples, but in all cases was below
the Colville criterion and Washington DOE sediment quality values
(table 6). Pesticides were not detected in any sample.
    Copper was detected in all samples, and in all cases was below
sediment quality values. Three samples exceeded the Colville copper
criterion, but were below the sediment quality standard proposed by
Michelsen (2003).
    Arsenic exceeded the Colville criterion in 11 of the 15 samples;
and 4 of 15 exceeded Washington DOE's lower sediment quality value. All
arsenic concentrations were below levels known to cause adverse
effects; however, several of the arsenic concentrations were in the
range where there could be a potential for adverse effects. Samples
from the 2007 study contained higher concentrations of each trace metal
than corresponding samples from the 2002 study (Johnson, 2002). This
was likely due to the 2007 sediment samples containing more fine
organic particles mixed with the sand and silt.
    Fine organic particles were most evident in the 2007 study in a
freeze core sample taken from between 5.0 and 6.6 feet deep near the
site of the new intake structure. This sample had a darker color, finer
texture, an organic odor, visible organic material in various stages of
decomposition, and higher concentrations of arsenic and copper. This
core sample was collected from the area of the reservoir where buried
sediments are most likely to be disturbed during project construction.
To a lesser degree, deposits of fine organic material were observed in
a patchy distribution in areas throughout the reservoir and on sandbars
downstream from Enloe dam.
    In addition to the analysis of contaminant concentrations in the
sediment, the same contaminants were analyzed in the water column using
the Dredging Elutriate Test to mimic water column concentrations that
could occur if sediments were disturbed by dredging (table 7). As with
the bulk sediment samples, pesticides were not detected in any
elutriate sample. Cadmium was detected at the detection limit in
several samples, but was well below the water quality criteria in all
samples. Arsenic was detected in all samples, but was also well below
the water quality criteria. Copper was detected in all samples, and
exceeded both chronic and acute criteria in 5 of the 8 primary samples.
All elutriate samples exceeded the arsenic and copper concentrations in
the ambient water sample from mid-reservoir.

                      Table 7--Summary of Preliminary Enloe Dam Sediment Elutriate Results
                                          [Source: Okanogan PUD, 2008a]
----------------------------------------------------------------------------------------------------------------
                                                                               Microgram per liter ([mu]g/L)
         PMX sample ID               ARI sample ID         Depth (feet)   --------------------------------------
                                                                             Arsenic      Cadmium       Copper
----------------------------------------------------------------------------------------------------------------
Shallow Core Samples:
----------------------------------------------------------------------------------------------------------------
    EDSG01....................  07-16494-LK86A........  0 to 1...........         12.5          0.2         12.1
    EDSG02....................  07-16495-LK86B........  0 to 1...........         29.1          0.2         28.2
----------------------------------------------------------------------------------------------------------------
VanVeen Grab Samples:
    EDSG03....................  07-16496-LK86C........  0 to 0.5.........          5.6     \a\ 0.2U          4.6

    EDSG05....................  07-16497-LK86D........  0 to 0.5.........         20.9          0.2         28.1
    EDSG06....................  07-16498-LK86E........  0 to 0.5.........          7.5         0.2U          9.9
    EDSG08 \b\................  07-16499-LK86F........  0 to 0.5.........          6.4         0.2U          6.5
----------------------------------------------------------------------------------------------------------------
Freeze Core Samples:
----------------------------------------------------------------------------------------------------------------
    EDSC04-0-4................  07-16099-LK13A........  0.0 to 5.0.......          5.3         0.2U          4.7
    EDSC04-4-8................  07-16100-LK13B........  5.0 to 6.6.......         53.6          0.2         52.2
    EDSC04-8-12...............  07-16101-LK13C........  6.6 to 8.0.......          6.3         0.2U          4.6
    EDSC08-0-4 \c\............  07-16102-LK13D........  0.0 to 5.0.......          5.1         0.2U          3.4
    EDSC08-8-12 \d\...........  07-16103-LK13E........  6.6 to 8.0.......          7.7         0.2U          6.2
----------------------------------------------------------------------------------------------------------------
Ambient Water Sample:
----------------------------------------------------------------------------------------------------------------
    07-16054-LK07A............  EDW01.................  3.5..............          3.6         0.2U          0.9
----------------------------------------------------------------------------------------------------------------
Water Quality Criteria:
----------------------------------------------------------------------------------------------------------------
    Acute, aquatic life.......  ......................  .................          360     \e\ 1.82      \e\ 9.2
    Chronic, aquatic life.....  ......................  .................          190     \e\ 0.64      \e\ 6.5
----------------------------------------------------------------------------------------------------------------
Notes:
\a\ Results with ``U'' were not detected in the sample at the accompanying detection limit.
\b\ Duplicate of EDSG06.
\c\ Duplicate of EDSC04-0-4.
\d\ Duplicate of EDSC04-8-12.
\e\ Criteria adjusted for 52 mg/L hardness (Washington DOE, 2005).

<IP_ADDRESS> Environmental Effects

Water Quantity

    The existing dam has an uncontrolled spillway that passes all
inflow. Okanogan PUD proposes to install new crest gates on the dam and
install an intake channel adjacent to the dam crest to divert river
flows to a new powerhouse and tailrace that would return flows to the
Similkameen River approximately 480 feet downstream of the dam. The
tailrace would discharge downstream of the falls, which is located
approximately 370 feet downstream of the dam. Okanogan PUD proposes to
operate the project in a run-of-river mode with no water storage for
hydropower purposes; however, it has agreed to comply with interim
ramping rate recommendations by Interior, Washington DFW, NMFS, and
American Rivers et al. (see section <IP_ADDRESS>, Aquatic Resources,
Environmental Effects).
    Okanogan PUD proposes to provide minimum flows of 10 or 30 cfs in
the 370-foot-long bypassed reach. American Rivers et al. recommends
flow releases to the bypassed reach to adequately protect aquatic
resources in the river and other designated beneficial uses in
accordance with Washington state law for the Similkameen River.\14\
According to the code, this would consist of a minimum flow of 400 cfs
during winter months up to a high flow of 3,400 cfs in the late spring/
early summer.
---------------------------------------------------------------------------

    \14\ Washington Administrative Code WAC 173-549-020
Establishment of minimum instream flows.
---------------------------------------------------------------------------

Our Analysis

    Because the project would operate in a run-of-river mode with only
minor flow variation caused by ramping rate restrictions, there would
be no effect on the flow regime downstream of the project, compared to
historical conditions. The issue of minimum flow releases for the
bypassed reach is discussed below in this section and in sections
<IP_ADDRESS>, Aquatic Resources, Environmental Effects, and <IP_ADDRESS>,
Aesthetic Resources, Environmental Effects.

Water Quality

Water Temperature (WQ-01)

    Okanogan PUD proposes to operate the crest gates to maintain the
reservoir levels between elevation 1,048.3 feet and 1,050.3 feet msl 99
percent of the time. The proposed crest gate operation would result in
a small increase in the reservoir surface area (less than 12 percent)
and larger increases in reservoir average depth (20 percent) and volume
(21 percent) up to 10 months a year and may affect water temperature in
the project reservoir. Okanogan PUD proposes to monitor water
temperature at three locations for 5 years to determine if the crest
gate operation causes an increase in the 7-DADMax water temperature in
the reservoir compared to the river upstream of the reservoir.
    Interior, NMFS, and American Rivers et al. comment that increased
reservoir size and area would result in more exposure to the sun, which
would result in higher water temperatures above the dam and downstream
of the dam, potentially affecting anadromous fish habitat. Interior
recommends a study of the effects of the Enloe Project on water
temperature. NMFS recommends that water temperatures be monitored for 5
years with annual reporting, and American Rivers et al. requests more
information about the effects of the project on temperature and water
quality.
    The British Columbia Ministry of Environment (Ministry of
Environment) comments that the project would not adversely affect water
temperature in Canadian waters and that water quality standards would
not be compromised as a result of project operations. The Ministry of
Environment supports Okanogan PUD's measures to monitor water
temperature in the reservoir and compensate for the potential decrease
in production by including habitat enhancements, tailrace relocation,
and entrainment studies.

Our Analysis

    Results of vertical temperature profile measurements (September 14
and 15, 2006) show that water temperature varied less than 0.6 [deg]C
from near surface to near bottom of the existing reservoir, indicating
virtually no stratification in the reservoir during late summer
(Okanogan PUD, 2008a). Comparisons of 7-DADMax temperatures indicated
that water temperatures did not increase through the project area by
more than 0.3 [deg]C at any time during the 2006 monitoring study (see
figure 2), and decreased throughout the project area after reaching
peak levels in late July. Based on these results, it appears that solar
radiation did not warm the existing reservoir pool any more than the
relatively shallow river reaches, with similar temperature patterns
among all stations. Substantial warming probably did not occur because
the existing reservoir is narrow and river-like in character. The
proposed project would increase the reservoir surface area by about 27
percent, comparing the existing reservoir at dam crest elevation to the
proposed reservoir level during low-flow operations (see table 4). The
actual increase in area would be from 60 to 76 acres, and the reservoir
would remain a relatively small, narrow reservoir, unlikely to
experience significant additional solar warming. In addition, the
reservoir mean depth and volume would increase (table 4), which would
act to counter any solar warming, in that more heat input would be
required to effect a change in temperature. Okanogan PUD also proposes
planting riparian vegetation along the reservoir to provide shading
(discussed in section <IP_ADDRESS>, Terrestrial Resources). Additional
shading would reduce the amount of surface water exposed to solar
warming. All these factors would act to minimize any heat gain and
prevent any increase in water temperatures during the summer low-flow
months. The greatest increase in reservoir size would occur during
high-flow spill periods (table 4), but reservoir residence time would
be short (only 45 minutes at the mean annual peak flow of 16,100 cfs),
so there would be little opportunity for solar warming, even if warm,
sunny conditions occurred during high-flow periods, which is not
common.
    Studies conducted in the Similkameen River downstream of the dam
indicate that water temperatures naturally increase during the summer
with potential for lethal effects on salmonids (Okanogan PUD, 2008a).
Based on our analysis, we conclude that construction and operation of
this run-of-river hydroelectric project would have little effect on the
existing water temperature pattern in the river, or affect compliance
with water quality standards for water temperature.
    Okanogan PUD would monitor water temperature for at least the first
5 years following license issuance to determine if the proposed
increase in reservoir elevation and surface area are having an
influence on water temperature in the reservoir and Similkameen River
downstream of the dam. This measure would provide a water quality
benefit. Development of the monitoring sites would be done after
consultation with the TRG. The annual data resulting from this study
could be used for adaptive management purposes and to design any
required mitigation for any adverse effects on water temperature that
may be observed. It would be appropriate for the Okanogan PUD to file a
report with the Commission at the end of five years evaluating the need
for continued monitoring and/or measures would ensure that the water
quality is maintained at a level that will support aquatic resources at
the project.

Dissolved Oxygen (WQ-02 Through WQ-04)

    Okanogan PUD proposes to inject air into the turbine draft tubes to
increase DO in the plunge pool/tailrace, which may be used by
anadromous fish as a holding pool and thermal refugia during the
critical summer season (figure 4). The aeration vents would not be used
during high spring flows when high TDG is a concern and DO
concentrations are not low. Okanogan PUD would monitor DO levels during
the first 5 years of project operations to determine the optimal time
after high flows have receded in the early summer to provide aeration
in the draft tubes.

[GRAPHIC] [TIFF OMITTED] TN17MY11.003

    Okanogan PUD proposed to locate the project tailrace so that the
discharged water circulates in the plunge pool below the falls. The
average annual tailrace flows, as simulated by Okanogan PUD, would be
similar in wet and normal water years (table 8).
    NMFS recommends that at the start of project operations, Okanogan
PUD should monitor DO concentrations at the powerhouse intake and below
the falls and continue monitoring for the term of the license.

                               Table 8--Simulated Average Annual Tailrace Flow for Three Normal and Three Wet Water Years
                                                              [Source: Okanogan PUD, 2009c]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                         Normal years                               Tailrace flow  (cfs)                Wet years               Tailrace flow  (cfs)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1989..........................................................                           842                          1991                         1,406
1993..........................................................                           896                          1996                         1,298
2000..........................................................                         1,051                          1997                         1,066
--------------------------------------------------------------------------------------------------------------------------------------------------------

Our Analysis

    During the warm summer months, DO is naturally low in the
Similkameen River. DO levels upstream and downstream of the project can
drop below 8 mg/L, which is the minimum state standard set to protect
salmonid fisheries. Currently, water passing over Enloe dam goes over
the falls, which increases the DO concentration by about 1 mg/L,
although this may vary depending on river flow and water temperature.
Under Okanogan PUD's proposal, water that is diverted for generation
would be routed around the falls and would not be naturally aerated as
now occurs. Okanogan PUD's proposal for draft tube aeration would
ensure protection of DO, despite loss of aeration by diverting flows
into the powerhouse rather than over the falls. Monitoring below the
powerhouse would assess the effectiveness of this measure and would
ensure that water discharged to the project tailrace would meet state
standards of 8 mg/L DO or higher at all times.
    Discharging powerhouse flows into the plunge pool would provide
circulation to prevent stagnation and water quality degradation during
the low flow summer months. The circulation pattern in the plunge pool
may change as the tailrace flows would enter the pool approximately 90
feet downstream from the falls at an angle. However, this change in
pattern should not affect water quality or substantially

affect fish distribution in the pool. During high flow periods when
water is passing over the dam and the falls, as well as through the
powerhouse, flow patterns in the plunge pool would be more similar to
current conditions, although there would be some reduced flow over the
falls, and thus potentially reduced TDG levels. DO levels would be high
during high-flow periods and heavy spillage over the dam and falls.
    Okanogan PUD's proposal to monitor DO levels during the first 5
years of project operations to determine the optimal time--after high
flows have receded in the early summer--to provide aeration in the
draft tubes would not meet the NMFS recommendation to monitor DO over
the term of the license.
    Monitoring DO during the first 5 years of operation would provide
good information on possible project effects on DO, but if water
quality standards are not met regularly, additional monitoring and
alternative measures may provide additional useful information.
Consultation with the TRG as to the need for an extension of the
monitoring period, as well as in determining the location of the DO
monitoring sites would ensure the proposal addresses the concerns of
the agencies and the Commission.

Total Dissolved Gases (WQ-02 and WQ-04, FISH-09)

    TDG concentrations measured between May 26 and May 30, 2006, were
below the 110 percent saturation water quality criterion in the lower
reservoir (RM 9.1) and between the dam and the falls (RM 8.9), but
exceeded the criterion below the falls (RM 8.8) and below the railroad
trestle at the mouth of the canyon downstream from the project area (RM
6.7). TDG concentrations increased substantially--an additional 12 to
14 percent of saturation--in water flowing over the falls. The increase
in TDG below the falls is due to the additional turbulence caused by
the falls and plunging flow into a deep pool where the increased
pressure causes air bubbles to dissolve into solution.
    Resident and anadromous fish can be negatively affected by
supersaturated TDG levels. The tolerance of anadromous salmon and
steelhead to TDG supersaturation varies greatly by life stage. Eggs
appear to be quite resistant to high TDG levels, while yolk-sac fry are
particularly vulnerable (Weitkamp and Katz, 1980). Juvenile fish appear
more sensitive to TDG saturation with increasing size.
    Okanogan PUD proposes to divert water from the reservoir, through
the turbines, and discharge flows downstream of the falls into the
plunge pool. Okanogan PUD would monitor TDG concentrations at the
project intake and in the plunge pool below the falls for a 5-year
period after license issuance to determine the effects of the proposed
operations on TDG levels at these locations.
    NMFS concurs with the proposal and adds that Okanogan PUD should
maintain the ability to monitor TDG for the term of the license.
    The Ministry of Environment comments that TDG levels are expected
to decrease as a result of project operations, which may benefit
downstream salmonids. American Rivers et al. requests more information
about potential water quality effects, including potential effects on
TDG during times of higher water temperatures.

Our Analysis

    Water diverted for power production would be discharged into the
plunge pool below the falls and would reduce spillage and plunging
flows over the falls, in turn decreasing TDG levels. Some flows would
continue over the falls when inflow to the reservoir exceeds 1,600 cfs
and excess flow is spilled over the dam. During these conditions,
powerhouse operation would continue and would act to reduce TDG
concentrations downstream of the falls. The beneficial reduction in TDG
would be directly related to the proportion of river flow that is
diverted through the powerhouse. For normal water years, substantial
reductions in TDG would be expected during all but a few days around
the annual peak flow. The recently proposed minimum flow releases of 10
or 30 cfs from the dam would maintain a small flow release over the
falls during periods when most of the river flow is diverted for power
generation. This volume of flow, however, would be much lower than
flows that now occur over the falls (see table 2), so there still would
be reductions in TDG compared to existing conditions.
    Normal turbine operation would not increase TDG except when air is
introduced in the turbine draft tube to protect DO concentrations
downstream during the summer months (see below). However, this would
typically occur after high flows have receded and high TDG is no longer
a concern.
    Any changes in TDG levels would have the potential to affect
resident juvenile UCR steelhead and other species in the plunge pool
and in the lower Similkameen River year-round. Okanogan PUD proposes to
monitor TDG at the powerhouse intake and in the plunge pool below the
falls for a period of 5 years. These data would be used to monitor the
effects of the project on TDG levels and to determine if alternative
measures are needed. This measure would provide a water quality
benefit; however, it would be appropriate for the Okanogan PUD to file
if a report with the Commission at the end of five years evaluating the
need for continued monitoring and/or measures would ensure that the
water quality is maintained at a level that will support aquatic
resources at the project.
    It would also be appropriate for Okanogan PUD to select the sites
for TDG monitoring in consultation with the TRG.

Sediment Management (WQ-05 and WQ-08)

    A 2007 licensing study that included sediment elutriate analyses
indicated that water quality standards for copper could be exceeded if
sediment is disturbed during proposed project construction and
operation (Okanogan PUD, 2008a). The shallowest part of the reservoir
is adjacent to the proposed intake location, and there is concern that
sediment in this location could be mobilized during excavation of the
intake channel and by project operations. Okanogan PUD proposes to
excavate as much of the intake channel as possible in the dry, because
underwater excavation poses the greatest risk of mobilizing sediment.
To contain any resuspended sediments that may occur, Okanogan PUD
proposes to install a floating silt barrier to contain sediments around
construction areas.
    As we've said in section 3.3.1, Geology and Soils Resources,
Okanogan PUD also proposes other measures to mitigate any effects of
erosion and sediment mobilization during construction. Excavated
material would be placed in a lined stockpile and tested for arsenic,
copper, cadmium, zinc, and lead. Okanogan PUD would develop a sampling
and analysis plan based on the chemical characteristics of
representative samples from established stockpiles, and the results
would be compared with relevant state criteria to determine if
materials could be disposed of onsite, in a licensed solid waste
landfill, or in a landfill licensed for the disposal of state-
designated dangerous waste.
    Okanogan PUD also proposes a Vegetation Plan that would include
hydroseeding of the disposal sites, in addition to the seeding and
other methods that would be used to revegetate all areas of exposed
soil as per the site revegetation requirements.

    Washington DOE recommends that the sediment excavated from the
intake channel entrance be tested for arsenic, copper, cadmium, zinc,
and lead, and the results compared to the MTCA Method A water quality
criteria of the EPA's Maximum Contaminant Level. Washington DOE also
recommends storing excavated material onsite until it is characterized,
then dispose of it in an appropriate manner based on analysis results
and including a sampling and analysis plan.
    In response to the agency comments and recommendations, Okanogan
PUD proposes to develop a Spill Response Plan and a Storm Water
Pollution Prevention Plan to be filed with the Commission within one
year of license issuance. The Spill Response Plan would be implemented
at the beginning of project construction.

Our Analysis

    Project construction has the potential to resuspend sediments
during excavation of the intake channel and installation of other
project facilities. This construction and any reservoir erosion due to
fluctuating water levels could cause short-term turbidity plumes,
release of contaminated sediments, and downstream sedimentation.
    To avoid resuspension of sediments to the extent possible, Okanogan
PUD would conduct as much of the excavation in the dry as possible. To
avoid mobilizing resuspended sediments downstream of the reservoir
during any instream excavations, Okanogan PUD would place a floating
silt barrier to contain suspended sediments. We expect Okanogan PUD's
other proposed measures, including the Spill Response Plan, the Storm
Water Pollution Prevention Plan, testing excavated materials for
arsenic, copper, and cadmium contamination, and employing BMPs, would
reduce the risk for short-term degradation of water quality and aquatic
habitat during construction, including critical habitat for UCR
steelhead and EFH for Chinook salmon.
    To estimate the likelihood of sediment transport occurring during
project operations, Okanogan PUD constructed a two-dimensional
hydraulic model of the reservoir using the program River 2D.\15\ Models
were developed for combinations of flow and forebay geometry,
including: 2,200 cfs under existing and proposed conditions; 10,200 cfs
under existing conditions; and 16,100 cfs under existing and proposed
conditions. The modeled range of flows spans the range of flow
magnitudes over which the 1-D impoundment hydraulic model predicted a
transition from potential deposition to potential erosion. The model
incorporates two assumptions: (1) Horizontal flow direction would not
change with changes in bed topography, and (2) threshold velocities do
not change with depth.
---------------------------------------------------------------------------

    \15\ The River 2D model, methods, and results are detailed in
Okanogan PUD (2008a), appendix e.2.3, section 4.2.6.
---------------------------------------------------------------------------

    The volume and weight of potential erosion/deposition were
estimated for each flow condition, assuming a characteristic grain size
of approximately 0.6 mm, an erosion/transport threshold of 1 foot per
second and a deposition threshold of 0.1 foot per second, and a
constant bulk density of sand equal to 100 pounds per cubic foot. The
results of the River 2D model are consistent with the expectation that
the addition of the intake channel would change flow velocities within
the reservoir near the intake. The intake channel causes the flow to
veer southeast toward the intake at both 2,200 and 16,100 cfs.\16\ The
model also indicates that increased velocities would be likely just
upstream of the pinch point that defines the upstream end of the
forebay (the lower end of the reservoir immediately adjacent to the
intake channel). The model predicts very high velocities in the intake
channel at both modeled flow volumes, indicating that sediment
transport and potential erosion would likely occur under the proposed
operations.
---------------------------------------------------------------------------

    \16\ The median annual flood discharge that would occur on
average once every 2 years is 16,100 cfs.
---------------------------------------------------------------------------

    The results of this model-based analysis suggest that the Enloe
reservoir currently undergoes an annual cycle of erosion and
deposition, and that the additional erosion and sediment deposition
that would occur at relatively low flows due to project operations
would be minimal, compared to the amount of erosion and deposition that
occurs every year during peak flows. At higher flows, the additional
erosion and deposition under proposed operations would also be minor.
    Okanogan PUD acknowledges uncertainties associated with this
analysis ; however, the general pattern shown by the model is probably
reasonable. Sediment builds up in the forebay during relatively low
flow portions of the year and is largely flushed out during annual peak
flows. This general pattern would likely continue during proposed
project operations, with increased levels of erosion and decreased
levels of deposition occurring in the lower end of the reservoir near
the dam and intake channel. The predicted small increases in reservoir
erosion and decreases in deposition during proposed project operations
indicate that some sediment deposition (sand and silt) would increase
in the lower gradient reach of the lower Similkameen River (RM 0-4.7)
(Okanogan PUD, 2008a). Increased deposition of fine sediment would
modify aquatic habitat if measurable deposition was to occur, and could
result in downstream contamination if the reservoir sediment
transported downstream of the falls is contaminated. That potential,
however, seems unlikely, because the River 2D model did not predict a
significant increase in erosion, which would be required to mobilize
contaminated sediment that has been deposited in the reservoir for many
years. The mound of sediment observed in the lower end of the reservoir
during low-flow bathymetric surveys is likely a transient feature that
does not contain legacy sediments from early in the impoundment's
history, and thus would not contain high contaminants levels (Okanogan
PUD, 2008a).
    Increased deposition of fine sediment in the lower Similkameen
River could have a negative effect on the spawning and rearing areas
used by anadromous salmonids and affect water quality for other
downstream beneficial uses. The potential effects on listed species are
discussed in section 3.3.5, Threatened and Endangered Species.

Spill Plan (WQ-07)

    Okanogan PUD proposes to develop and implement a Spill Plan
including spill prevention, containment, and clean-up plan at project
initiation to reduce potential effects of accidental spill.
    BLM recommends Okanogan PUD develop and implement, after
consultation with the BLM, a hazardous substances plan (essentially
same as Spill Plan) for oil and hazardous substance storage, spill
prevention, and clean up prior to any activity that may affect the BLM-
administered public lands. BLM recommends the plan address both
construction and ongoing operations and maintenance of the proposed
Enloe Project. At a minimum, the plan would: (1) Outline Okanogan PUD's
procedures for reporting and responding to releases of hazardous
substances, including names and phone numbers of all emergency response
personnel and their assigned responsibilities; (2) outline Okanogan
PUD's procedures for timely identification and remediation of spills,
including procedures in the event that

personnel are not present on-site 24-hours a day; (3) identify and
maintain a cache of spill cleanup equipment sufficient to contain any
spill from the proposed Enloe Project; (4) call for Okanogan PUD to
provide BLM with a report specifying the location of spill clean-up
equipment on the BLM-administered public lands and the location, type,
and quantity of oil and hazardous substances stored in the proposed
Enloe Project area; and (5) require that Okanogan PUD inform BLM
immediately as to the nature, time, date, location, and action taken
for any spill affecting the BLM-administered public lands.

Our Analysis

    In accordance with 40 CFR 112.1 of the EPA's regulations, a spill
prevention control and countermeasure plan is required to be in place
for any facility where unburied storage capacity exceeds 1,320 gallons
of oil or a single container has a capacity in excess of 660 gallons.
In addition to the on-site storage of lubricants and other oil
products, transformers are likely oil-cooled and would be of sufficient
capacity to exceed the 1,320 gallon threshold that would require a
plan. The Spill Plan proposed by Okanogan PUD and further described by
BLM would provide a quick reference to procedures and notifications in
case of oil spills to reduce the possibility of oil or other hazardous
substances reaching the BLM-administered land and the Similkameen River
if a spill occurs. Development and implementation of the Spill Plan
after consultation with BLM and Washington DOE would minimize the
potential for petroleum products to enter the project waters in the
event of a spill.

Minimum Flow Proposal

    As we previously described in sections 1.3.2 and 2.2.4, by letter
filed October 28, 2010, Okanogan PUD proposes minimum flows for the
bypassed reach immediately downstream of Enloe dam. Okanogan PUD also
proposes: A monitoring program for DO and water temperature for the
bypassed reach for a period of time postconstruction; an adaptive
management program to enhance DO and water temperatures should
monitoring indicate that water quality standards are not being met;
determining critical flow thresholds for downramping rates based on
monitoring and field observations prior to operations; and determining
a means for releasing minimum flows at Enloe dam.

Our Analysis

    Okanogan PUD's proposal would provide a minimum flow of 30 cfs from
mid-July to mid-September, and 10 cfs the rest of the year into the
bypassed reach.
    Providing a minimum flow of 10 and 30 cfs would ensure that some
flow is passing over Enloe dam and falls at all times, even during the
lowest flow months of the year when the project hydraulic capacity
would allow diversion of the entire river flow for power generation.
Effects on water quality would be related to potential changes in DO
levels and water temperature. As we previously discussed, DO levels in
the Similkameen River do not always meet the state standard of a
minimum of 8 mg/L under existing conditions, although the falls act to
aerate flows passing over them. Diversion of most of the river flow
through the powerhouse during lower flow periods would reduce the
aeration effect that now occurs over the falls. A study conducted by
Okanogan PUD found that under current conditions, DO levels of water
plunging over the falls increase by approximately 1.0 mg/L.\17\
Maintaining some flow in the bypassed reach and over the falls would
continue to provide some natural aeration in this project reach,
although flows of 10 and 30 cfs are relatively low and may not
contribute substantially to aeration below the project tailrace.
Okanogan PUD's proposal to aerate the water in the project draft tubes
would be able to increase DO levels by 1.0 mg/L or more and would be
able to offset the loss of this natural increase in DO.
---------------------------------------------------------------------------

    \17\ See Okanogan PUD letter filed on November 10, 2010.
---------------------------------------------------------------------------

    Water temperatures in the Similkameen River upstream and downstream
of the project area are marginal for salmonid habitat under existing
conditions, and often exceed state standards for salmonid spawning,
incubation, and rearing. Effects of the proposed minimum flow on water
temperature could occur by passage of a relatively low flow (10 and 30
cfs) in the bypassed reach, exposing it to solar radiation and warming
during the summer months, further reducing the suitability of salmonid
habitat in the river. On November 10, 2010, Okanogan PUD filed an
analysis of the effects of the proposed minimum flow on water
temperature, which concluded that the passage of that flow through the
bypassed reach would not result in a measurable increase in water
temperature at the base of the falls, even under the lowest river flow
conditions.\18\ Okanogan PUD, however, also concluded that a
temperature increase of 0.5 to 1.0 [deg]C could occur in the bypassed
reach if the proposed minimum flow was allowed to pass over the entire
face of Enloe dam in a thin sheet flow.\19\ Passing the minimum flow
through a pipe or a smaller gate to the base of the dam instead of
providing it as a sheet flow over the dam could prevent this
temperature increase. We find Okanogan PUD's analysis reasonable and we
agree that passing this minimum flow would likely have a minor effect
on water temperature downstream of the falls, assuming that the minimum
flow is provided via a pipe or small gate at the dam.
---------------------------------------------------------------------------

    \18\ See Okanogan PUD letter filed on November 10, 2010.
    \19\ State water quality standards are that a water temperature
increase should not exceed 0.3 [deg]C.
---------------------------------------------------------------------------

    Okanogan PUD's proposal for DO and temperature monitoring for a
period of time postconstruction would allow for a characterization of
the water quality in the bypassed reach under the proposed minimum
flows of either 10 or 30 cfs. Consultation with the TRG to determine
the length of DO and temperature monitoring in the bypassed reach, and
adaptive management could help to develop means to protect water
quality in this reach.
    Similarly, Okanogan PUD had previously proposed to implement the
ramping rates recommended by the resource agencies downstream of the
tailrace. Additionally, they have proposed to identify critical flow
thresholds for downramping rates in the bypassed reach to protect
aquatic resources in the bypassed reach during project start-up and
shutdown. The topography of the bypassed reach is such that there are
areas where fish would likely be stranded if spillage over the dam is
reduced at a rate that does not allow fish to successfully vacate these
areas. The best way to determine these critical flow thresholds would
be by field observations as proposed.
    Okanogan PUD provided preliminary designs for alternative minimum
flow release structures and stated that the preferred option would be a
gate and release pipe using one of the two existing penstock intakes
from the abandoned hydro station at the dam. This would minimize the
potential for water temperature increases in the minimum flow releases.
Okanogan PUD stated, however, that it and the resource agencies have
not yet come to agreement on the final design of the flow release
structure, and it proposes further consultations with the agencies to
finalize the design. We agree that a flow

release structure consisting of a gate and pipe using one of the former
penstock intakes would be the best option, because it would minimize
any potential water temperature increases, would allow placement of the
flow discharge at a point below the dam that would provide the greatest
environmental benefit, and would provide the best control of the flows
to be released. We also agree that the final design of this structure
should be developed in consultation with the resource agencies
(Washington DOE, Washington DFW, FWS, NMFS, BLM, and the Colville),
prior to filing the design with the Commission for approval.
<IP_ADDRESS> Cumulative Effects
    Historical land use in the Similkameen River drainage includes a
legacy of mining, timber harvest, grazing, and agriculture. Commercial
mining has probably had the greatest impact on the Similkameen River
water quality. One of the largest mines in the area was the Kaaba-Texas
Mine, located several miles upstream of Enloe reservoir near the
community of Nighthawk. The mine operated from the late 1890s until
1954 and discharged tailings directly into the Similkameen River until
1946. In 1999, the EPA removed and disposed of approximately 81,000
cubic yards of contaminated mine tailings from the mine site.
    Today the dominant land use is agriculture, grazing, and
recreation. A number of orchards, vineyards and a public golf course
are located along the Loomis-Oroville Road. The area is unfenced open
range generally leased for grazing.
    The water quality of the Similkameen River has improved since the
commercial mining has been discontinued in the drainage area above the
project, and with the EPA efforts to remove contaminated mine tailings
at the Kaaba-Texas Mine. However, much of the sediment contained in
Enloe reservoir was deposited when upstream mining activities were
active, and contains some arsenic, copper, and cadmium.
    The construction and operation of the project could result in a
number of effects that when added to conditions already present in the
basin, could have negative environmental effects. Project construction
of the intake channel has the potential to remobilize contaminated
sediments. Petroleum products stored and used during construction and
during project operations could be released to project waters. The
increase in reservoir surface area increases the potential for slightly
higher water temperatures in the reservoir. Erosion from project
construction could cause increased turbidity and sedimentation.
Measures proposed by Okanogan PUD and additional staff recommended
measures, however, would minimize the effects on water quality and the
potential for cumulative effects during the construction and operation
of the proposed project.
3.3.3 Aquatic Resources
<IP_ADDRESS> Affected Environment
    The fisheries resources information presented in this section is a
combination of recent and historical reports produced by state and
federal resource agencies; investigations by universities and
consulting groups; literature reviews; file materials from state and
federal agencies; and ongoing studies. These materials were
supplemented by information from Okanogan PUD studies that were
conducted in consultation with NMFS, FWS, Washington DFW, Washington
DOE, and the Colville from 2005 through 2008.
    The Similkameen River is approximately 72 miles long and originates
in the Cascade Mountains of British Columbia, Canada. The 27-mile reach
of the Similkameen River between the U.S./Canadian border and the
Okanogan River flows through semi-arid mountainous terrain. The
licensing study area extends from the confluence of the Similkameen and
Okanogan Rivers upstream to Shanker's Bend at RM 10.1. Enloe dam is
located immediately upstream of the Similkameen Falls,\20\ about 8.8
miles upstream from the confluence with the Okanogan River. Enloe dam
is approximately 18 miles downstream of the U.S./Canadian border.
---------------------------------------------------------------------------

    \20\ Also known as Coyote Falls.
---------------------------------------------------------------------------

Downstream of the Dam

    The river below the falls is divided into three reaches based on
habitat conditions and channel morphology. Reach 1 (RM 0-4.7) is a low
gradient (<0.1 percent), braided channel. The dominant substrates are
cobble and gravel with areas of sand and boulders. The majority of
salmonid spawning occurs in this reach, although gravel is relatively
scarce--limiting the amount of spawning habitat. Reach 2 (RM 4.7-7.1)
has a wider active channel than reach 1 and a few side channels. The
gradient is low to moderate (0.1 to 2 percent; average 0.4 percent).
The substrates are cobble, sand, and boulders. Reach 3 (RM 7.1-8.8) is
a canyon reach. The channel gradient in reach 3 averages greater than 2
percent. Although the dominant substrate is bedrock, sand deposits
occur in the center of the channel.
    The Similkameen River supports anadromous and resident fishes below
the falls. Native species in the lower river include summer-run Chinook
salmon, sockeye salmon, UCR steelhead, bridgelip sucker, largescale
sucker, mountain whitefish, longnose dace, northern pikeminnow, redside
shiner, rainbow trout, and unidentified sculpin species (table 9). Non-
native species include common carp, largemouth and smallmouth bass, and
black crappie. The relative abundance (percent composition) of these
species is shown in table 10.

             Table 9--Native and Non-Native Fishes in the Similkameen River Based on Snorkel Surveys
                                          (Source: Okanogan PUD, 2008a)
----------------------------------------------------------------------------------------------------------------
                                                         Okanogan PUD                           ENTRIX  (2007)
           Common name             IEC beak  (1984)         (1991)          ENTRIX  (2006)      (upstream only)
----------------------------------------------------------------------------------------------------------------
Chinook salmon..................  ..................  ..................  D.................  ..................
UCR Steelhead/rainbow trout.....  D & U in Canada...  D.................  D.................  ..................
Sockeye salmon/kokanee..........  U kokanee.........  ..................  ..................  ..................
Bridgelip sucker................  D.................  U.................  U.................  U (unidentified
                                                                                species)
Largescale sucker...............  ..................  D & U.............  D & U.............  U (unidentified
                                                                                species)
Sculpin spp.....................  D.................  D & U.............  D & U.............  U

Northern pikeminnow.............  D.................  U.................  D.................  U
Longnose dace...................  D & U.............  ..................  ..................  U
Redside shiner..................  ..................  U.................  D & U.............  U
Burbot..........................  ..................  U.................  ..................  ..................
Mountain whitefish..............  D.................  D & U.............  D.................  U
Chiselmouth.....................  ..................  ..................  ..................  U
Peamouth........................  ..................  ..................  ..................  U
Smallmouth bass.................  ..................  ..................  U.................  ..................
Largemouth bass.................  ..................  D & U.............  D & U.............  U
Black crappie...................  D.................  D.................  ..................  ..................
Common carp.....................  ..................  ..................  ..................  U
Yellow perch....................  ..................  ..................  ..................  U
----------------------------------------------------------------------------------------------------------------
Note: D = downstream of Enloe dam; U = upstream of Enloe dam.

         Table 10--Numbers and Percent Composition of Native and Non-Native Fishes in the River Downstream of Enloe Dam Based on Snorkel Surveys
                                                              (Source: Okanogan PUD, 2008a)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                 Reach 1  RM 0-4.7              Reach 2  RM 4.7-7.1             Reach 3  RM 7.1-8.8
               Common name               ------------------------------------------------------------------------------------------------   % of  Total
                                                Aug             Sep             Aug             Sep             Aug             Sep            catch
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sucker spp..............................              29             314              53             176               0               1            22.0
Largemouth bass.........................              42              25              12               7               0               0             3.3
Smallmouth bass.........................             101              92              32               8              13              20            10.2
Sculpin spp.............................               3               6               1               3               0               0             0.5
Common carp.............................               0              13               0               0               0               0             0.5
Minnow spp..............................             472             737               5               0               0               0            46.6
Northern pikeminnow.....................              15               0              21              21               0               1             2.2
Juvenile UCR steelhead/rainbow trout....             115              77              16               8               3               1             8.4
Adult UCR steelhead/rainbow trout \a\...               0               3               0               0               0               0             0.1
Sockeye salmon..........................               0              13               2               0               0               0             0.6
Chinook salmon..........................               0              33               0               0               0               0             1.3
Mountain whitefish......................              41              47               1              24               0               0             4.3
    Totals..............................             818           1,360             143             247              16              23             100
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ The numbers of adult anadromous fish observed during the 2006 snorkel surveys were not considered representative of population strength because
  adult anadromous fish are most abundant in the river during their respective spawning migrations, and the survey occurred outside of the spawning
  migration period.

    The summer-run Chinook salmon in the Similkameen River enter the
river from July through late September. In its February 26, 2010
letter, NMFS stated that adults are known to hold in the plunge pool
below the falls until spawning takes place in October through early
November, peaking in mid-October from RM 0 to RM 8.8. There are no
known spawning areas within the project area. Most of the Chinook
salmon spawning occurs in the lower 5 miles of the river. Washington
DFW counted 1,660 Chinook salmon redds in 2004 and 1,423 in 2005 in the
lower Similkameen River. Based on these redd counts, Washington DFW
estimated Chinook spawning escapement \21\ to be approximately 4,169
fish in 2004 and 3,770 in 2005. Chinook fry emergence occurs in January
through April; juveniles emigrate to the ocean within 1-4 months after
emergence, when water temperatures begin to increase.
---------------------------------------------------------------------------

    \21\ Anadromous adults returning to spawn.
---------------------------------------------------------------------------

    Washington DFW operates a Chinook salmon rearing and acclimation
facility called Similkameen Pond at RM 3. Juveniles are released from
the pond in mid-April to mid-May.
    Sockeye salmon enter the Columbia River from late May to mid-June,
and migrate into the Okanogan River. Sockeye salmon spawn primarily in
the main stem of the Okanogan River upstream of Lake Osoyoos in Canada,
typically in October. Fry emerge in March through May and move
downstream to Lake Osoyoos. The juveniles rear in the lake for 1-2
years before emigrating to the ocean, usually in May. Although some
sockeye have been reported in the lower Similkameen River, there is no
sockeye spawning habitat in the river.
    Chinook salmon and sockeye salmon pre-spawn mortalities in the
Similkameen and Okanogan Rivers have been associated with high water
temperatures. Dead female Chinook salmon were examined to estimate pre-
spawn mortality in the Similkameen River from 2004-2006. Examinations
in 2004 and 2005 indicated approximately 1 percent of females died
prior to spawning. This percentage could vary

depending on the annual flow and temperature conditions.
    High water temperatures can also delay upstream migration of the
anadromous salmonids into the Okanogan River and can lead to the pre-
spawn mortality noted above, or affect the timing of spawning. UCR
steelhead, Chinook salmon, and sockeye salmon enter the cooler
Similkameen River and migrate as far upstream as the falls during the
summer months. The larger, deeper pools (e.g., the plunge pool below
the falls) and areas with overhead structure (e.g., large woody debris,
bridges) are the preferred holding habitat until temperatures in the
Okanogan River decrease and these species can commence their spawning
activities. These spawning delays can adversely affect reproductive
success by extending incubation and fry emergence into time periods
with less suitable conditions for survival, or by shortening the
rearing period for juvenile fish prior to their emigration to the
ocean.
    During snorkel surveys, Okanogan PUD observed juvenile steelhead/
rainbow trout in the side channels of reach 1 and 2, where water
temperatures were several degrees cooler than the surrounding water. In
dry years, flow in the side channels is intermittent, resulting in
dewatered segments. Small amounts of large woody debris also occur in
these reaches, and sections of the river have been channelized and
diked, particularly near Oroville.
    In its February 26, 2010, letter, Interior stated that historically
significant runs of anadromous Pacific lamprey may have occurred in the
project area, and the lamprey has had economic and cultural
significance to local Native American tribes. Lamprey larvae are filter
feeders that burrow into fine silty substrate in the lower velocity
areas of streams (Wydoski and Whitney, 1979). Pacific lamprey remain in
the larval stage for 5 to 6 years before they metamorphose and migrate
to the ocean as predatory adults. The adult stage is generally short
(less than 1 to 2 years) (Moyle, 2002).
    Probable suitable Pacific lamprey spawning and rearing habitats are
present in the Similkameen River below the dam; however, recent
attempts to document adult lamprey have been unsuccessful. Washington
DFW has documented unidentified larval lamprey in the hatchery ponds on
reach 1, close to the confluence with the Okanogan River. In 2006, the
Colville collected adult and juvenile lamprey from screw traps in the
Okanogan River, downstream of Salmon Creek. Unconfirmed lamprey redds
were observed in the middle reach of the Okanogan River in 2008.

Proposed Bypassed Reach

    The 33-foot-long, 20-foot-high Similkameen Falls below Enloe dam is
a natural barrier to upstream salmonid fish passage. The falls presents
less of an impediment to Pacific lamprey since they use their oral
disks to attach to surfaces allowing them to withstand higher current
velocities. Fish habitat in the 370-foot-long, bedrock-boulder
dominated bypassed reach between the dam and the falls is limited and
it was believed that there are few, if any fish in this reach. A
snorkel survey of the bypassed reach between Enloe dam and the head of
Similkameen Falls was conducted in August 2006. No fish were observed.
The dominant substrate is bedrock strewn with large boulders; smaller
substrate occurred in sparse patches. There is no overhanging
vegetation or large woody debris.
    On September 15, 2010, another snorkel survey and hook and line
sampling was conducted by Washington DOE and DFW biologists in the
plunge pool downstream of Enloe dam, with participation by Okanogan PUD
representatives and a biologist from the Colville (report included in
filing from Donald H. Clarke, Counsel to Public Utility District No. 1
of Okanogan County, to Kimberly Bose, Secretary, FERC, November 10,
2010). Flow conditions did not allow a complete survey of the plunge
pool, and only the east side of the pool was safely accessible to
swimmers. Biologists observed small numbers of juvenile suckers,
smallmouth bass, rainbow trout, and one sculpin, and two rainbow trout
and a northern pikeminnow were captured by hook and line. No anadromous
species were observed. Fish were observed actively feeding, indicating
that the plunge pool is used as feeding habitat by resident fish
species when flow conditions allow. Fish observed in the pool likely
gained access to the pool by dropping downstream from upstream of Enloe
dam.
    Flow in the bypassed reach becomes extremely turbulent during high
water. Fish in the bypassed reach and plunge pool would encounter
extreme flow conditions during high flow, and may be flushed downstream
of the falls unless they can access flow refugia within the plunge pool
or elsewhere in the bypassed reach. Aquatic benthic macroinvertebrates
would also be subject to high shear stress and scour during high flows.

Upstream of the Dam

    Habitat in Enloe reservoir consists mostly of sand and silt
substrate with some gravel. Cobble occurs at a few sites near the
upstream end. From the middle of the reservoir to the upstream end the
banks are also relatively steep. There is more shallow water habitat in
this section of the reservoir, although the majority of habitat is
still deep and open water. Overhanging vegetation that provides shade
and cover is limited along the reservoir, and includes a few large
willows. Small amounts of aquatic vegetation and a few patches of
submerged grasses occur in the reservoir. Large woody debris is scarce;
the most common habitat structure and cover were steep rock walls,
submerged boulders, and partially submerged boulders along the
shoreline.
    There are fewer fish species in Enloe reservoir than in the river
below the dam (tables 9 and 11). Native resident fishes in the
reservoir include chiselmouth, peamouth, bridgelip sucker, largescale
sucker, mountain whitefish, longnose dace, burbot, northern pikeminnow,
redside shiner, and unidentified sculpin species. Non-native species
include largemouth bass, smallmouth bass, yellow perch, and common
carp. Native rainbow trout are found upstream of the project boundary
in Canada but were not found in the project reservoir but were found in
the bypassed reach.
    Most of the species in Enloe reservoir are introduced, non-native
fish that are better adapted to warmer, slower velocity habitat (table
11). Most fish captured in the reservoir were small and were found in
shallow areas associated with the limited presence of cover (mostly
vegetation). The larger fish, mostly northern pikeminnow, chiselmouth,
and unidentified suckers, use open water areas of the reservoir. No
rainbow trout and very few mountain whitefish were found in the
reservoir, likely due to a combination of northern pikeminnow
predation, warm water temperatures, and lack of cover. Introduced
warmwater species, such as largemouth bass, yellow perch, and common
carp, may be spawning in the reservoir littoral zones, but more likely
are transported to the reservoir from upstream sources such as Palmer
Lake.

                    Table 11--Numbers and Percent Composition of Native and Non-Native Fishes in the Reservoir Upstream of Enloe Dam
                                                              [Source: Okanogan PUD, 2008a]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   2006                                                    2007
                                         ---------------------------------------------------------------------------------------------------------------
                                                Beach seine             Minnow trap                 Beach seine     Minnow trap      Gill net
               Common name               ------------------------------------------------  % of  ------------------------------------------------  % of
                                                   Aug.    Sept.           Aug.    Sept.   total   March   July    March   July    March   July    total
                                          July 7    11      14    July 7    11      14     catch    22      24      22      24      22      24     catch
--------------------------------------------------------------------------------------------------------------------------------------------------------
Suckers spp.............................      22       1       0       0       1       0    10.2       0       2       1       0       0       2     6.7
Sculpin spp.............................       2       0       0       0       0       1     1.3       0       0       1       0       0       0     1.3
Largemouth bass.........................      53      16       0       0       0       0    29.4       0      16       0       0       0       0    21.3
Chiselmouth.............................       0       0       0       0       0       0       0       0       0       0       0       0       8    10.7
Common carp.............................      14       0       0       0       0       0     6.0       0       0       0       0       0       0       0
Minnow spp..............................      68      28       1       4       4       3    46.0       0       1       0       1       0       0     2.7
Peamouth................................       0       0       0       0       0       0       0       0       0       0       0       0       2     2.7
Northern pikeminnow.....................       0       0       0       0       0       0       0       0       0       0       3       0      16    25.3
Redside shiner..........................       2       0       0       1       0       0     1.3       1       0      11       1       0       0    17.3
Longnose dace...........................       0       0       0       0       0       0       0       3       3       0       0       0       0     8.0
Yellow perch............................      13       1       0       0       0       0     6.0       0       1       0       0       0       0     1.3
Mountain whitefish......................       0       0       0       0       0       0       0       0       2       0       0       0       0     2.7
                                         ---------------------------------------------------------------------------------------------------------------
    Totals..............................     174      46       1       5       5       4     100       4      25      13       5       0      28     100
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Similkameen River aquatic benthic macroinvertebrate data were
collected by Vinson (1994) from three riverine sites between the
Canadian border and the project area at RMs 12, 16, and 17. Eighty-five
taxa were collected; 10 taxa made up 80 percent of the total sample
(table 12). The majority of macroinvertebrates collected were
chironomid larvae (50.3 percent relative abundance). Ephemeroptera from
the family Ephemerellidae accounted for 19 percent of the relative
abundance; Trichopterans represented 9 percent.

      Table 12--Aquatic Benthic Macroinvertebrate Taxa Found in the Similkameen River Above Enloe Reservoir
                                          [Source: Okanogan PUD, 2008a]
----------------------------------------------------------------------------------------------------------------
                                                                                Portion of
            Order                   Family         Sub-Family         Genus         sample  (%)    Cumulative  %
----------------------------------------------------------------------------------------------------------------
Diptera......................  Chironomidae...  Orthocladiinae.  ...............            21.0            21.0
Diptera......................  Chironomidae...  Chironominae...  ...............            19.2            40.2
Ephemeroptera................  Ephemerellidae.  ...............  Ephemerella....            11.0            51.2
Diptera......................  Chironomidae...  Tanypodinae....  ...............             8.0            59.2
Trichoptera..................  Hydropsychidae.  ...............  Hydropsyche....             7.1            66.3
Ephemeroptera................  Baetidae.......  ...............  Baetis.........             5.4            71.7
Ephemeroptera................  Ephemerellidae.  ...............  ...............             2.6            74.3
Diptera......................  Chironomidae...  ...............  ...............             2.1            76.4
Trichoptera..................  Brachycentridae  ...............  Brachycentrus..             1.9            78.3
Oligochaeta..................  Tubificidae....  Naidinae.......  ...............             1.8            80.1
----------------------------------------------------------------------------------------------------------------

    There are no benthic macroinvertebrate data for Enloe reservoir or
the river below Enloe dam. It is likely that the reservoir benthic
macroinvertebrate community is less diverse than the riverine
community. A significant increase in non-insect taxa that are tolerant
of silt conditions, such as oligochaete worms and isopods, would be
expected in the reservoir. The macroinvertebrate communities in reaches
2 and 3 below Enloe dam are likely similar to communities found in the
upper Similkameen River. Reach 1 is a lower velocity, braided channel
with more fine sediment deposition; as such, it is likely to have a
higher percentage of taxa that burrow, swim, or sprawl, with a
corresponding reduction in the percentage of macroinvertebrates that
cling and/or crawl.

<IP_ADDRESS> Environmental Effects

Effects of Project Construction (WQ-05 Through WQ-08, FISH-01, BOTA-03
and BOTA-04, BOTA-07 Through BOTA-13)
    As proposed by Okanogan PUD, construction of the project access
road, intake channel, penstock, and powerhouse would require excavation
and placement of spoil using heavy equipment, blasting, and would be
supported by staging and laydown areas and fuel and lubricant storage
facilities.
    Okanogan PUD proposes a Blasting Plan that includes environmental
measures to minimize potential negative effects on anadromous and
resident fish that are in the large pool at the base of the falls. The
Blasting Plan incorporates the following mitigation measures to avoid
adverse effects on anadromous and resident fish:
     Small charges would be set off with time delays to
minimize peak vibration and avoid creating excessive pressure waves and
noise. Threshold criteria for pressure waves and noise have been
adopted in the Blasting Plan to avoid potentially harmful levels of
pressure and noise.
     Impacts would be minimized by timing near- and in-water
blasting to coincide with the lowest water levels (low flows) combined
with lowest potential for fish occupation in the area.
     Blast scheduling would avoid periods when federally listed
or sensitive fish species are present.
     Blasting adjacent to the river would take place prior to
spring high flow or during fall low flow.

     The amount of time that near- or in-water construction and
blasting occurs would be minimized when the downstream end of the
tailrace channel is excavated. During this period, construction
activities would be expedited to reduce the amount of time fish may be
exposed to the effects of blasting activities.
     Impacts would be minimized or avoided by removing as many
fish as practical from the area adjacent to the proposed blasting and
installing an exclusion barrier downstream of the potentially affected
area to prevent entry of additional fish into the affected area.
     Mechanical excavators with hydraulic rock hammer
attachments would be used in lieu of blasting to trim the excavation,
excavate rock in areas unsuitable for blasting, and to excavate loose
rock. Okanogan PUD would remove residues from the blasting operation to
the extent practical.
     Hydrophones would be used to monitor pressure waves from
blasting that could affect fish.
     Creation of hydrostatic pressure waves greater than 100
kilopascals (or about 14.5 pounds per square inch), or noise levels
exceeding 190 decibels (dB) would be avoided, as practical.
    In response to a comment by Washington DFW, Okanogan proposes to
station biological monitors in the field during blasting to observe
mortalities or changes in fish behavior that might make them more
susceptible to predation.

Our Analysis

Blasting

    The large, deep plunge pool downstream of the falls is an important
habitat feature for anadromous and resident fishes that is not found
elsewhere in the Similkameen River. Blasting would expose fish in the
plunge pool to short-term physiological stress, sublethal injuries,
mortality, or predation. Okanogan PUD's proposed Blasting Plan, as
described above, however, would minimize these impacts and be
protective of the fishery.
    Additionally, Okanogan PUD proposes to capture anadromous and
resident fish in the pool and relocate them prior to blasting
activities. This measure would physically remove fish from areas where
they could experience negative impacts due to blasting and would be
protective of these fishes. This measure could result in some negative
effects to captured fish including net abrasion, short-term
physiological stress, sublethal injuries, mortality, and increased
predation during transport or as a result of relocation to less optimal
habitat. Capture of all individuals in the plunge pool prior to
blasting would be difficult given the size of the pool (400 feet long
by 80 to 100 feet wide by = 20 to 30 feet deep) and the
turbulence created by the falls. Accordingly, some fish, particularly
smaller fish such as juvenile UCR steelhead, would remain in the deep
pool below the falls after removal efforts. After fish are removed from
the plunge pool, Okanogan PUD proposes to use netting across the
Similkameen River which would exclude fish from re-entering the blast
zone.
    Okanogan PUD proposes visual biological monitoring during
construction of project facilities to observe mortalities or changes in
fish behavior that might make them more susceptible to predation. As
noted by Okanogan PUD, however, the physical characteristics of the
plunge pool would make it difficult to effectively monitor the area of
impact effectively. If biological monitors were to observe mortalities
or changes in fish behavior, Okanogan PUD also does not specify what
kind of mitigative or protective actions may be taken.
    Direct or indirect effects of the blasting activities may cause
mortality or injury to ESA listed UCR steelhead. Additional discussion
of effects on the listed steelhead is included in section 3.3.5,
Threatened and Endangered Species.
    Because there is the potential for adverse effects on a listed
species (UCR steelhead) and other high-value species (Chinook salmon),
and that the PUD's proposed Blasting Plan does not resolve all issues
related to blasting, it would be appropriate for Okanogan PUD to
consult with the TRG in preparing a final Blasting Plan. Involving the
agencies that comprise the TRG in the development of this plan would
ensure that all appropriate protection measures are considered and
included in the plan.

Sediment

    In its comments in response to the REA notice, NMFS recommends that
Okanogan PUD prepare and implement a Soil Erosion Control Plan to guide
project construction, as well as operation and maintenance of the
project. Interior recommends that Okanogan PUD develop and implement an
Erosion and Sedimentation Management Plan.
    In response to the agency comments and recommendations, Okanogan
PUD developed a Spill Response Plan, and a Storm Water Pollution
Prevention Plan. The Spill Response Plan would be implemented at
project initiation. Construction plans would be developed prior to
construction, and BMPs would be implemented during all construction
activities.
    To characterize the hydraulic transport of sediment through the
project, Okanogan PUD performed a modeling effort using the River 2D
model. Results of the modeling show that sediment in the Enloe
reservoir undergoes an annual deposition and erosion cycle.\22\
Currently, Enloe dam acts as a sediment trap during low flow portions
of the year (May through December). Low flow periods correspond with
low water velocities from which suspended sediments settle creating a
mound of sediment in the project reservoir near the dam. This mound of
sediment is washed downstream annually during high flow periods
(January through April) when flows increase by a factor of 20 or more.
This sediment is washed over the dam and is transported downstream.
---------------------------------------------------------------------------

    \22\ Results of the River 2D modeling are found in Appendix
E.2.3 to the license application.
---------------------------------------------------------------------------

    Under Okanogan PUD's proposed project operations, sediment
transport in the Similkameen River in the project vicinity would change
slightly. Okanogan PUD would divert up to 1,600 cfs through the
turbines during all months of the year. Sediment carried in this water
would still be transported downstream of the dam, but would do so by
traveling through the powerhouse as opposed to spilling over the dam.
Flows during the high flow portion of the year (January through April),
which range on average from 1,800 to 7,600 cfs, would exceed the
hydraulic capacity of the project and would spill over the dam as now
occurs, transporting sediment out of the project reservoir and into the
river downstream of the powerhouse. Overall, proposed project
operations would have a negligible effect on the current cycle of
sediment transport in the Similkameen River.
    Sediment deposited in the reservoir may be transported downstream
during project construction and operation. This could result in both
adverse and beneficial impacts to aquatic resources. Adverse impacts
would include short-term turbidity plumes and sedimentation from
construction activities, which could cause mortality of eggs, fry, and
juvenile fish due to smothering or abrasion. Re-suspension of
contaminated sediments containing elevated levels of copper or arsenic
could also occur and lead to bioaccumulation of those contaminants in
fish eggs or fry, and to acute levels in predatory fish and
insectivores such as salmonids and bass. Additional sedimentation,
however, could provide

benefits to species that utilize sediment as their preferred habitat.
Species potentially benefiting from any deposition of finer sediments
would include the Pacific lamprey (which spends most of its life in
freshwater submerged in fine sediment), western ridged mussel, western
pearlshell mussel, western floater mussel, and the California floater.
    Okanogan PUD proposes to develop and implement two measures to
mitigate for possible sediment inputs into the Similkameen River due to
project construction and operation: an ESCP and a CSMP. These measures
are discussed in more detail in section <IP_ADDRESS>.
    As noted above, Okanogan PUD proposes a Spill Response Plan and a
Storm Water Pollution Prevention Plan. The Spill Response Plan includes
practices to minimize the chances or severity of spills of hazardous
materials into or near the river. These practices include: Ensuring all
hazardous materials are safely sealed; immediate cleaning-up of all
spills according to manufacturer's recommended methods; properly
disposing of waste generated during spill clean-up; and notifying state
and local government agencies in the case of spills. The Storm Water
Pollution Prevention Plan includes BMPs to prevent erosion in project
areas and to protect water quality. The BMPs include: visibly marking
land-clearing limits; controlling river flow rates; installing sediment
controls such as straw bales, silt fences, and sandbags; stabilizing
all disturbed soils; protecting slopes in the project area; stabilizing
all channels and outlets; and controlling pollutants. The
implementation of these plans would be protective of aquatic resources
in the project area.
    Okanogan PUD's proposals for an ESCP, a CSMP, a Spill Response
Plan, and a Storm Water Pollution Prevention Plan would minimize short-
term degradation of aquatic habitat during construction, including
critical habitat for UCR steelhead and EFH for Chinook salmon.

Enhancement Measures for Resident Fish (FISH-02)

    Okanogan PUD proposes to construct light-colored boulder clusters
to improve mountain whitefish habitat and recreational fisheries in the
river upstream of the reservoir.
    Washington DFW and Interior do not recommend the proposed boulder
clusters because they say that the mountain whitefish fishery above the
dam is limited and restricted to the winter months. Interior also
suggests that the boulder placement may create a further heat sink and
increase water temperatures. Instead, these agencies as a part of the
Fisheries Enhancement Plant and Resident Fish Habitat Management Plan,
respectively, recommend annual stocking of catchable-size sterile,
triploid rainbow trout to provide a greater recreational fishery
opportunity. Okanogan PUD states that it would consider contributing up
to $60,000 (the cost of the boulder clusters) towards a trout stocking
program for the term of the license, if the other state and federal
agencies, tribes, and other stakeholders agree.
    The Colville, the Ministry of Environment, and the Canadian Parks
and Wilderness Society have expressed concerns throughout the licensing
process that Washington DFW and Interior's recommendation for
introduced fish stocks of triploid rainbow trout would pose an
unacceptable risk to resident fishes due to potential disease transfer
and competition for food and space, while providing a limited
contribution to the recreational fishery.

Our Analysis

    Most of the fish in the reservoir are non-native species that are
better adapted to warmer, slower velocity habitat than native coldwater
salmonids. The project would raise the elevation of the reservoir by 4
feet, and therefore, would result in more lake habitat and less
riverine habitat for coldwater resident fishes. Okanogan PUD's proposal
to add boulder clusters upstream of the reservoir to provide habitat
for resident fish would create a small amount of pool habitat behind
the clusters that could be utilized by native mountain whitefish.
However, very few whitefish (0 in 2006; 2 in 2007) have been found in
the reservoir during recent surveys, likely due to a combination of
northern pikeminnow predation, warm water temperatures, lack of cover,
and the sand-silt substrate. Therefore, it is unlikely that the
proposed boulder clusters would provide much of any benefit to the very
limited mountain whitefish fishery in this section of the river.
    The introduction of hatchery fish stocks would provide a limited
and short-term contribution to the recreational fishery, because water
quality and high water temperatures in the Similkameen River would only
allow a fishery during the cooler months of the year. The stocked
rainbow trout may not survive in the river during the warmer summer
months. Stocked rainbow trout would also pose a threat to native fish
stocks in the United States and Canada due to potential for disease
transfer and competition for food and habitat. In addition, although
fish occurring in the river upstream of the project may utilize the
project reservoir at times, the proposed run-of-river operation of the
reservoir would likely have no effect on these species and would not
affect the riverine habitat upstream of the reservoir.

Large Woody Debris Transport (FISH-03)

    Large woody debris is an important component of a healthy stream
ecosystem. Large trees that fall into streams perform an important role
in forming pools, regulating storage and routing of sediment, and
trapping spawning gravel. Large woody debris also provides complex fish
habitat that increases carrying capacity, high flow refugia for fish,
and substrate for macroinvertebrates. Enloe dam prevents the supply and
transport of all large woody debris from the upper Similkameen River
Basin to the lower river, except during high flows. The lower river has
low levels of large woody debris, and currently all wood that enters
the reservoir from the upper basin is either passed over the dam during
flood stage or removed from the reservoir and not returned to the river
below the dam. Lack of large woody debris from the upper basin may
contribute to a reduction in structural habitat complexity for fish and
macroinvertebrates downstream of the dam.
    Okanogan PUD proposes to allow large woody debris to pass over the
spillway during the annual flood flows; allow natural downstream
transport of the woody debris; and would transport some large woody
debris around the dam and place it in the river downstream of the dam,
if needed. Transport of large woody debris would occur once annually
during the recession of the annual high flow.
    Interior recommends a plan \23\ for the collection and relocation
(downstream transport) of large woody debris to be completed at least 1
year before the start of any land-disturbing or land-clearing
activities.
---------------------------------------------------------------------------

    \23\ As a part of their recommended Fisheries Enhancement Plan.
---------------------------------------------------------------------------

Our Analysis

    Okanogan PUD's proposal to allow natural wood passage over the dam
during large flood events when the crest gates on the spillway would be
fully open, and to supplement that supply of woody debris by
transporting large wood impounded by the dam to the

river below the dam, would provide additional anadromous and resident
fish and macroinvertebrate habitat and would increase productivity
downstream of the dam. Development of a large woody debris transport
plan after consultation with FWS, NMFS, Interior, Washington DFW, and
the Colville would help to guide implementation of the measures,
including providing direction on determining when such transport would
be required, the methods to be used for collection and transport of the
wood, and the best locations for release of the woody debris downstream
of the dam.

Intake Trashrack, Entrainment Studies, and Fish Monitoring (FISH-04 and
FISH-05)

    Entrainment into the intakes and passage through the turbines could
result in injury or mortality to resident reservoir fish that are
attempting to move downstream. Additionally, larger fish could become
impinged on the trashrack causing possible injury or mortality.
Okanogan PUD proposes to install a modified intake trashrack adjacent
to the existing dam overflow spillway with provisions for a low
velocity approach channel, and a trashrack at the intake with narrow
(1-inch) bar spacing to prevent entrainment of large fish. Okanogan PUD
also proposes to generate with Kaplan turbines, which generally cause
low mortality for any small fish entrained into the power flow.
Okanogan PUD proposes to file detailed design drawings of the modified
trashrack intake and the trashrack cleaning system no later than 180
days prior to start of construction. Okanogan PUD also proposes to
monitor adult and juvenile impingement and entrainment effects and to
conduct quarterly fish sampling over a 1-year period.
    Interior and Washington DFW recommend filing detailed design
drawings of an intake fish screen and a schedule to build the screen
before the start of any land-disturbing or land-clearing activities, as
well as a monitoring plan and corrective actions to minimize fish
impingement and entrainment.

Our Analysis

Impingement

    The proposed spillway would provide a 276-foot-long exit from the
reservoir for any downstream moving fish. During high-flow periods,
this route would have high approach velocities. By comparison, the
proposed power intake is a much smaller outlet with a lower approach
velocity. Diverting water from the spillway to the power intake would
likely draw some fish toward the intake and away from passage over the
spillway, potentially exposing these fish to impingement on the
trashracks or entrainment through the turbines. However, the modified
trashrack with 1-inch bar spacing proposed by Okanogan PUD would be
designed so that smaller fish can pass safely through the racks without
becoming impinged, and larger fish (greater than 6 inches in length)
would be discouraged or prevented from passing through the racks and in
turn the turbines.
    Okanogan PUD calculated the average monthly water velocities \24\
at the trashrack to examine impingement risk for larger fish. Estimated
monthly average velocities at the trashrack ranged from 1.06 feet per
second (fps) to 2.91 fps, depending on the intake flow and associated
river flow and reservoir elevation. Swimming speeds of fish known to
reside in the project reservoir were collected for comparison to water
velocities at the trashrack, to examine if resident fish would be able
to swim away from the trashrack, thus avoiding impingement. Nine of the
fish species known to reside in the reservoir \25\ are able to reach
burst speeds \26\ of between 4.6 and 10 fps (for adult life
stages).\27\ These species would be able to swim away from the
trashracks in all months of the year, avoiding impingement. From April
to July, predicted velocities at the trashrack would average 2.65 fps,
which could result in impingement for two species known to reside in
the reservoir. Northern pikeminnow and chiselmouth have burst swimming
speeds of 2.5 fps, and thus would be susceptible to impingement if
unable to avoid the intake flow. Fishes impinged would be subject to
injury and mortality, which would be most likely to occur from April to
July.
---------------------------------------------------------------------------

    \24\ See Okanogan PUD AIR response filed on July 21, 2009. In
this AIR response, Okanogan incorrectly stated that burst speed for
largemouth bass is 2.1 fps. Appalachian Power Company (2009)
collected critical swimming speeds for largemouth bass from 10
studies identified in the literature and were able to estimate that
the burst speed of juvenile largemouth bass is between 3.2 to 4.3
fps, while adults would be capable of faster speeds.
    \25\ These species are bridgelip sucker, largescale sucker,
unidentified sunfish species (genus Lepomis), common carp, yellow
perch, rainbow trout, Kokanee salmon, and mountain whitefish.
    \26\ A speed that can be maintained for a short period of time,
typically seconds.
    \27\ See Okanogan PUD AIR response filed on July 21, 2009.
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Entrainment

    Reservoir sampling showed that most of the small, resident fish in
the reservoir are found in shallow water areas with cover. Accordingly,
very few small fish are expected to be in the area of the intake
because of unsuitable habitat (deep open-water habitat with steep,
almost vertical walls). Two native species--chiselmouth and northern
pikeminnow--would have the greatest potential of occurring near the
intake. Native suckers, mountain whitefish, and introduced species,
such as largemouth bass, carp, and yellow perch, may also be present
near the intake. Resident rainbow trout were not found between the
U.S./Canadian border and Enloe dam during recent studies, and probably
would not occur near the intake. Because the population density of fish
in the reservoir is low, and the project would have narrow-spaced
trashracks, the rate of entrainment at the project would likely be low
resulting in undetectable effects of the population levels of resident
fishes in the reservoir. Additionally, the survival rates of fish that
would be susceptible to entrainment (those less than 6 inches in
length) after passing through the turbines have been estimated to be
84% to 95%.\28\
---------------------------------------------------------------------------

    \28\ Survival rates were calculated by Okanogan PUD using the
U.S. Department of Energy's Advanced Hydro Turbine System Program.
---------------------------------------------------------------------------

    Okanogan PUD proposes to monitor seasonal variation in entrainment
susceptibility, entrainment mortality, and fish populations in the
reservoir after project construction. Both entrainment levels and
mortality of entrained fish are expected to be very low. Additionally,
effects of project entrainment on reservoir populations are expected to
be minor. Therefore, these data collection efforts likely would not
produce useful data. Additionally, Okanogan PUD did not specify if
these monitoring efforts would lead to adaptive management, if needed,
to adjust the proposed measures to reduce any adverse effects
associated with operation of the intake.
    The agencies recommendation for a fish screen did not include any
design details, so we are unable to determine how the performance of
the proposed narrow-spaced trashrack would compare to a fish screen.
However, Okanogan PUD's proposed trashrack would achieve the same goal
of physically excluding the majority of fish approaching the intake.
Fish screens cost much more than trashracks to build, install, and
maintain. The proposed trashrack would achieve similar results at a
much lesser cost than a fish screen. To ensure that the applicant's
proposed narrow-spaced trashrack achieves similar exclusionary goals of
a fish screen, it would be beneficial for Okanogan PUD to consult

with the fisheries agencies during the final design of the intake
structure and trashracks. By including some or most of the design
features of a fish screen into the design of the narrow-spaced
trashrack, fish protection would be provided concurrently with
protection of the generating equipment from the influx of trash.

Tailrace Net Barrier and Tailrace Video Monitoring (FISH-06 and -07)

    Operation of the project may attract upstream migrating fish into
the turbine discharge flow. It is expected that this behavior could
result in UCR steelhead or anadromous salmonids attempting to enter the
draft tubes and swim through the draft tubes to an area near the
turbine runner blades. Fish may be injured or killed by impact with the
spinning runner blades during partial load operation when velocities
downstream of the turbine may be low enough for the fish to reach the
turbine runner. Okanogan PUD proposes to design (after consultation
with NMFS), install, and operate a net barrier at the outlet of each
draft tube. Okanogan PUD proposes to maintain the nets and to develop a
written operation plan in consultation with NMFS. Okanogan PUD also
proposes to monitor the effectiveness of the tailrace barrier nets
through the use of underwater videography. Okanogan PUD would submit
draft and subsequent design plans to NMFS; obtain NMFS' approval of
design specifications for the tailrace barrier; and file a detailed
design of the barrier nets with the Commission at least 180 days before
the start of any land-disturbing or land-clearing activities. Okanogan
PUD also proposes to develop and implement a postconstruction
evaluation and monitoring plan and an inspection and maintenance plan.
    NMFS recommends that when downstream oriented velocities in the
draft tube are less than or equal to 27 feet per second (the highest
burst swimming speed attainable by UCR steelhead) the tailrace barrier
should be in place and operated as designed. NMFS states that
development of the final detailed barrier designs (in consultation with
NMFS), including expected approach velocities, be completed 180 days
prior to the start of any land-disturbing activities. NMFS further
recommends that these final designs include a hydraulic evaluation of
the facilities; a written operation plan; a postconstruction evaluation
and monitoring plan; a contingency plan in the event the proposed
tailrace net barriers do not perform according to criteria; and an
inspection and maintenance plan.
    Washington DFW and Interior make similar recommendations regarding
the need for the tailrace barriers and consultation; however, these
agencies recommend the filing of detailed design drawings with the
Commission at least 1 year before the start of any land-disturbing or
land-clearing activities.

Our Analysis

    Of the fishes that are found in the area where the tailrace would
be located, UCR steelhead are the strongest swimmers, and therefore
would be most likely to be able to access the draft tubes while the
project is operating. Adult UCR steelhead are strong swimmers and are
reported to have a burst speed of 27 feet per second (Bell, 1986).
During full load operation, the water velocity immediately downstream
of the turbine runner blades would exceed this burst speed, creating a
velocity barrier that would prevent fish from reaching the area where
injury or mortality could occur. Installation of a net barrier at the
outlet of each draft tube, however, would provide a physical barrier to
prevent injury to fish during periods of reduced generation, when water
velocities would be lower than steelhead burst speed and too low to
maintain the velocity barrier.
    Okanogan PUD would use underwater video cameras during the peak
presence of UCR steelhead, Chinook, and sockeye salmon during the first
two years of operation, to monitor the openings of the net barriers.
The video would be reviewed to document if adult salmonids are able to
enter the area where barrier nets are deployed, and if so, if the nets
effectively prevent fish from moving further upstream into the draft
tubes, and if fish are able to safely exit the barrier net locations.
This measure would allow Okanogan PUD to monitor the effectiveness of
the tailrace barriers nets. It would also allow for adaptive
management, so that the tailrace barriers nets location or design could
be adjusted or operated in a more efficient or effective manner, if
possible. The use of underwater videography would ensure that
anadromous salmonids and resident fishes are protected from entering
the draft tubes where mortality or injury could result.
    It is expected that the final barrier design, the operation plan,
postconstruction evaluation and monitoring plan, and the inspection and
maintenance plan, to be developed after consultation with NMFS, and
filed with the Commission for approval, would provide sufficient
assurance that the proposed barrier net designs would provide adequate
protection to fish downstream of the proposed powerhouse.

Run-of-River Operations (FISH-08)

    Okanogan PUD proposes to operate the Enloe project in a run-of-
river mode. The 370-foot-long bypassed reach would receive a minimum
flow of 10 or 30 cfs (see below) during the lower flow months when
river flow is equal to or less than the hydraulic capacity of the
powerhouse. Powerhouse discharges would be returned to the river below
the falls.

Our Analysis

    The proposed run-of river operations would have no effect on water
quantity above the dam or downstream of the project powerhouse at the
base of the falls. This would be protective of the current fisheries
habitat in the lower Similkameen River downstream of the falls, as
river flows would be unchanged from current conditions.

Ramping Rates

    Okanogan PUD proposes to implement interim ramping rates based on
Washington State guidelines (Hunter, 1992) to protect aquatic resources
downstream of the tailrace (table 13). The ramping rates would apply to
changes in hourly water elevations associated with project operation
during normal powerhouse start-up and shut-down. Temporary
modifications to ramping rates may be needed to address operating
emergencies or planned outage.

                                        Table 13--Proposed Ramping Rates
                                             [Source: Hunter, 1992]
----------------------------------------------------------------------------------------------------------------
                  Season                           Daylight \a\                         Night \b\
----------------------------------------------------------------------------------------------------------------
February 16 to June 15...................  No ramping.................  2 inches per hour.
June 16 to October 31....................  2 inches per hour..........  1 inch per hour.

November 1 to February 15................  2 inches per hour..........  2 inches per hour.
----------------------------------------------------------------------------------------------------------------
Notes:
\a\ Daylight is defined as the period from 1 hour before sunrise to 1 hour after sunset.
\b\ Night is defined as the period from 1 hour after sunset to 1 hour before sunrise.

    Interior, Washington DFW, NMFS, and American Rivers et al.
recommend implementation of the ramping rates shown in table 13 for the
protection of aquatic resources. These agencies recommend that
temporary modifications of the ramping rates that may be needed due to
operating emergencies or planned outages should be developed by mutual
agreement among Okanogan PUD and the interested agencies and tribes. To
expedite these discussions, Okanogan PUD requests that these agencies
be required to appoint a single local representative who has the
authority to address such operational issues. If the interim ramping
rates are so modified, Okanogan PUD would notify the Commission, as
soon as possible, but no later than 10 days after each such incident. A
second issue regarding ramping rates was described in the applicant's
recent filings, related to ramping rates immediately downstream of
Enloe dam when spillage flows are reduced as the project powerhouse is
brought on line. The September 2010 snorkeling survey conducted by
Washington DFW and Washington DOE identified bedrock benches along the
shoreline of the plunge pool that could strand fish if spillage over
the dam was to be reduced at a rate where fish could not vacate that
habitat before it is dewatered. As a result, Okanogan PUD now proposes
to determine the critical flow thresholds related to dewatering of
these bedrock benches, based on field observations, so that appropriate
downramping of spillage flows can be made between those flow thresholds
(letter from Donald H. Clarke, Counsel to Public Utility District No. 1
of Okanogan County, to Kimberly Bose, Secretary, FERC, October 28,
2010).

Our Analysis

    Okanogan PUD proposes the interim ramping rates recommended by
Interior, Washington DFW, NMFS, and American Rivers et al., for the
protection, mitigation of damages to, and enhancement of aquatic
resources downstream of the powerhouse. Rapid flow reductions in a
stream channel, especially in low gradient stream areas, have the
potential to strand fish in dewatered areas including pools and side
channels. Fry and juvenile fish less than 2-inches-long are most
vulnerable to potential stranding due to weak swimming ability;
preference for shallow, low velocity habitat such as edgewater and side
channels; and a tendency to burrow into the substrate to hide. The
magnitude of change can also affect habitat use and the production of
macroinvertebrates that are vulnerable to drift or stranding. Side
channels are particularly susceptible to dewatering and disconnection
from the main channel as flows recede. As a result, young-of-the-year
salmonids that prefer to rear in side channels (e.g., UCR steelhead)
may be stranded.
    Based on Hunter (1992), we expect that the interim downramping
rates described in table 13 should protect Chinook salmon and UCR
steelhead redds and fry, and juvenile Chinook salmon, UCR steelhead,
sockeye salmon, and aquatic macroinvertebrates from stranding and
mortalities associated with flow fluctuations downstream of the
powerhouse. In addition, because the project would operate in a run-of-
river mode, any reductions in powerhouse flow would result in an
immediate increase in spillway flows, which would also enter the pool
at the base of the falls at about the same time that powerhouse flows
are reduced. Thus, the pool at the base of the falls and the
Similkameen River downstream of this pool would not experience wide
water level fluctuations under normal operations. This proposed
operation and the proposed ramping rates would also protect UCR
steelhead designated critical habitat and Chinook salmon EFH downstream
of Similkameen Falls.
    Recently proposed measures to limit downramping of spillage flows
immediately downstream of Enloe dam would protect any resident species
from potential stranding on bedrock benches along the shoreline of the
plunge pool. Identifying the critical flow thresholds and associated
water elevations in relation to the bedrock benches would allow
development of actual ramping rates between those flow thresholds.
Okanogan PUD proposes that these flow thresholds be determined by field
observations and monitoring prior to initiation of project operations,
but does not specify what the ramping rates would be once the flow
thresholds are determined. It would be appropriate to determine the
flow thresholds by field observations, because there have been no
detailed surveys of the river bathymetry or instream flow modeling in
the bypassed reach. Future ramping rates would still need to be
determined, as appropriate rates in the bypassed reach may not
necessarily be the same as those outlined in Hunter (1992). Therefore,
a study plan would be required that would describe how the flow
thresholds would be determined by field observation, and how future
downramping rates for the bypassed reach would be developed. This study
would need to be prepared in consultation with Washington DFW,
Washington DOE, FWS, and the Colville, and filed with the Commission
for approval.

Ramping Rate Compliance Monitoring

    Okanogan PUD proposes to use the existing Washington DOE gage in
the lower Similkameen River to monitor ramping rate compliance
downstream of the powerhouse. Interior, Washington DFW, NMFS, and
American Rivers et al. recommend that the location to measure
compliance should be determined by Okanogan PUD in consultation with
Interior, NMFS, Washington DOE, Confederated Tribes and Bands of the
Yakama Indian Nation (Yakama Nation),\29\ and the Colville, before
project operation begins.
---------------------------------------------------------------------------

    \29\ NMFS and Interior's 10(j) recommendation for compliance of
the ramping rates included consultation with the Yakama Nation.
---------------------------------------------------------------------------

Our Analysis

    The Washington DOE gage that Okanogan PUD proposes to use to
monitor ramping rate compliance on the lower river is located in
Oroville at river mile 5, nearly 4 miles downstream of the project
site. Sites for monitoring compliance with ramping rates should be
located in relatively close proximity to project discharges, so that
gage heights recorded reflect the water surface elevations immediately
downstream of the powerhouse. It is

unlikely that the existing DOE gage in Oroville would meet these
criteria, because any small fluctuations in discharge from this
proposed run-of-river project would likely be attenuated in the 4 miles
of river between the tailrace and the gage.
    Interior, Washington DFW, NMFS, and American Rivers et al.'s
recommendation that a monitoring site would need to be established as a
result of consultation between those parties and Okanogan PUD would
ensure that the location for monitoring ramping rate compliance would
be near the project and would adequately measure the ramping rates. The
result of this selection process could require the installation of a
new monitoring gage on the Similkameen River near the project's
tailrace. A plan detailing how Okanogan PUD would monitor compliance
with their proposed ramping rates, including the location selected for
doing so would be beneficial and would need to be filed with the
Commission for approval.

Flow Continuation

    Interior recommends development of a plan that would provide up to
48 hours of flow continuation in the event of emergency project
shutdown at the unmanned, remotely operated powerhouse. Interior also
recommends that the crest gates or flow continuation valves for each
penstock be designed to open automatically to provide outflow into the
lower river from a combination of the tailrace and spillway flows, so
that river flow never drops below the level of inflow to the reservoir.
Interior further recommends that the plan include detailed drawings and
flow capacities for the proposed crest gates or flow continuation
valves.

Our Analysis