As we continue our process of rebuilding and restoring our communities in the Estes Park area following the September flood, it may prove beneficial to delineate the specific terms used by the stakeholders in this process. It is to this purpose we are writing this week's column.

The term 100 year flood is defined as a flood that occurs statistically once every 100 years or has a one percent chance of occurrence in any given year. In other words, a 100 year flood has a one percent chance of being equaled or exceeded in any given year. The term does not imply that the flood will necessarily happen once every one hundred years. Likewise, a 500 year flood has a 0.2 percent chance of occurring in any given year. For every flood , we feel the need to use a relative label to describe it. Traditionally, with floods, we have described them by flood level, CFS and frequency. Flood level is a measure of how many feet 'above flood level' a given water surface has reached. For instance, the recent flood in the Big Thompson canyon was 1.5 feet above the flood level of the 1976 flood. This measure is obviously of great importance to potential flood victims since it measures how badly they will be affected by the flood waters. CFS refers to cubic feet per second in flow by the river or stream. It is equal to a volume of water one foot high, one foot wide flowing a distance of one foot in one second. Once CFS is equal to 7.48 gallons of water flowing each second. The last measurement component is frequency or 'probability of return'. This measures just how often a flood of any particular size can be expected. This is where the statistical measure of a 5, 10, 50, 100 or 500 year flood is applied.

It is noteworthy that the recent flood in our area might be considered a 50 or 100 year flood for the Fall River area yet possibly a 500 year flood on the Fish Creek area and both resulted from the same weather occurrence. This is indicative of the significance of hydrology, geology, flood plain and floodway configuration in the extent of damage sustained in a flood situation.

FLOOD PLAIN information is gathered by utilizing topographic base mapping, hydrologic analysis and hydraulic calculations to describe precise water surface profiles and flood plain delineations used in making land use decisions for zoning purposes.

A FLOOD INSURANCE RATE MAP (FIRM) is the official map of a community on which FEMA has delineated both special hazard areas and the risk premium areas applicable to the community. As an example, if you live in Zone A (as marked on the local FIRM map) it is considered subject to inundation by the 100 year flood event or 'base flood' and mandatory flood insurance purchase requirements apply. However, if you live in Zone D it is considered an unstudied area where flood hazards are undetermined but flooding is possible. No mandatory flood insurance purchase requirements apply but coverage is available in participating communities. Our local FEMA flood map is available by googling FEMA Flood Map Service Center and our map # is 08069C.

Another term frequently used in the process of remapping our area with revised flood insurance rate maps is FLOODWAY. This refers to the channel of a river or watercourse and the adjacent land area that needs to be obstruction free in order to discharge the flood water without increasing the water surface elevation. FREEBOARD is the distance in feet above a predicted water surface elevation intended to provide a margin of safety to compensate for unknown facts that could contribute to the calculated height of a flood. This would include debris and increasing run off due to urban development. This is the term that is used to indicate the required height above the predicted high water mark that a home owner would need to use in constructing the basement or lowest level in the house construction.

The Town of Estes Park currently has a temporary ban on any new construction or substantial remodels in the floodway but this is about to expire. The town's floodplain regulator has proposed adopting the State flood plain regulations in addition to using the 'high water mark' as the definition of the regulatory floodplain or current floodplain whichever is stricter. If the base flood is a 100 year event and Fish Creeks flood turns out to be close to a 500 year event then is using the high water mark for a 500 year event raising the bar too high? Should it be the high water mark less two feet or one foot? How long will it take to get revised floodplain maps: 2 years or five? The floodplain regulator has propsed using 2,000 feet as the maximum transition length for letters of map revisions to existing floodway delineations. In my opinion this seems excessive and will put an undue burden of cost on the first person trying to build on that section of the floodplain. When the National Flood Insurance Program (NFIP) was mandated to map all the floodplains in the U.S. it was obvious they needed to determine a standard 'size' flood in order to treat all communities equitably. If they used the "flood of record" for each community for mapping purposes, and eventually floodplain development control, it was seen as unfair because some 'unlucky' community may have seen a 500 year event recently while a neighboring community which is actually just as flood prone, hasn't had its 500 year event since records have been kept.

These are all community decisions we have to make and need to be discussed as a community. Should we put the creek or river back where it was or should we widen the floodway? If we think it is best to widen the floodway then how do we compensate people for lost property value. Do we wait years until we have new floodway maps? I for one certainly hope we can all agree on some compromise.