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Flood Insurance Study Repo!t Data Flood Insurance Study - Cooper Slough, Larimer County, Colorado Page 4 during storm events. In places, the width of the floodplain averages over 1,000 feet, although the depth of flooding is generally less than three feet 13xcept in areas where ponding occurs. Hydrologic data from stream gages were not available thus no discharge and recurrence intervals for majorfloocis along Cooper Slough could be determined. 2.4 Flood Protection Mei~sures (no change from FIS da::ed March 18, 1986) 3,0 ENGINEERING METHODS 3.1 Hvdroloqic Analvse~! Hydrologic analyses of Cooper Slough were carried out to establish the relationship between peak dischargE! and frequency for floods of selected recurrence intervals. The peak discharges for the 10-, 50-, 100-, and 500-year floocis for Cooper' Slough used in this study werE! established using the Storm Water Management Model (SWMM) as developed by the Environmental Protection Agency (EPA) and later modified by the Missouri River Division (MRD) of the U.S. Army Corps of Engineers (Reference 5). The original SWMM model for the Coopl3r SIQugh watershed was developed by Simons, Li, and Associates (SLA) for thEl "Cooper Slough Master Drainageway Implementation Plan" (Reference 6). This model has been revised to include the overflows fro 11 Soxelder Creek basin. Tile 1991 Soxelder Cree,k LMMP Flood Insurance Study (FIS) lists peak 100-year overflow discharges into the Cooper Slough basin, from the Soxelder Creek basin, at the following locations along 1-25: Larimer-Weld Canal Vine Drive low point elf 1-25 south of Vine Street C&S Railrcad State Highway 14 (Mulberry Street) TI,e peak discharges for the 10-, 50-, 100- and 50D-year storms flowing into Cooper Slough from Soxelder Creek at the above locations on 1-25 were obtained during a meeting with Mr. Gerald :Shultz of the USSR (Reference 7) Mr, Shultz prepared the Soxelder Creek hydraulic analysis and determined oVl3rflow peaks using weir calculations. The following table lists the peak discharges from the Soxelder Creek basin for each of the storm recurrence intervals at each location along 1-25 as given by Mr. Gerald Shultz, USSR.