Date of this Version
Nebraska Public Power District (NPPD) has monitored water quality since 1989 and fish populations since 1993 on the Niobrara River in Nebraska in the vicinity of Spencer Hydro during "flushing" or "sluicing" activities. These sluicing activities alter water quality in the river downstream, which can negatively impact fish populations. Higher numbers offish were sampled in 1995 when compared to 1993 and 1994. Of the 6,187 fish and 22 total species sampled above and below the hydro, six species comprised approximately 93 percent of the total sample. The most common species sampled were sand shiner, Notropis ludibundus (35.4%), red shiner, Cyprinella lutrensis (22.9%), flathead chub, Hybopsis gracilis (14.4%), carpsucker spp., Carpoides sp. (10.9%), bigmouth shiner, Hybopsis dorsalis (5.1%), and channel catfish, lctalurus punctatus (4.0%). Operational modifications instituted since 1989, such as opening the flood gates slower and dropping the pond at a slower rate, have reduced sluicing impacts and the hydro structure may not be limiting species diversity to the extent originally thought.