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GRIM302.5W Site - A smaller (13-acre) parcel just downstream of the SN wetland was also analyzed. This site is not connected to the SN wetland and floods less frequently. Overbank flooding occurs approximately every 3 to 4 years when flows exceed 19,000 cfs. Flooding enhancement opportunities are limited. Bank lowering or channel excavation could increase flood frequency to every 3 years at 18,000 cfs. GRSR296E Site -Located six miles downstream of the Jensen Bridge, a large 283-acre pasture bottomland site is protected from frequent flooding by a high man-made levee road set 10 to 20 feet back from the river along the said properties. The levee prevents overbank flooding for flows up to the 100-year event. By simply removing this levee, the flooding frequency could be improved to every 2 out of 3 years, once flows reach 13,000 cfs. There are, however, existing buildings and access roads that would be affected by any flooding enhancement activities. Mitigation measures and/or the abandonment of the buildings would need to occur if the site were restored. This site would retain some water after flooding flows receded under the flooding enhancement scenario. The flooding at this site affects three property owners. GRSL288N -Located just downstream of the Bonanza Bridge bottomland site, a 98-acre bottomland area extends across three parcels of land. The site floods from the downstream end at flows of approximately 19,600 cfs, 1 out of every 3 years, statistically. Flooding enhancement could improve flooding frequency to 2 out of 5 years at 18,000 cfs. Access roads and structures would be affected by the increase in flood frequency, however, these buildings appear to be abandoned, and the site used infrequently. Gunnison River GUBC14S Site- Located approximately one mile downstream of the Highway 141 Bridge near Whitewater, the GUBC14S site provides 59 acres of floodable area. The gravel pit site, protected by a man-made dike, could simply by restored by notching the dike at upstream and downstream locations. River sediments could be allowed to flow through these notches and eventually fill in the deep pit to create a site more favorable to endangered fish. Restoration activities would not negatively impact any adjacent properties. A • structure, or protected inlet and outlet, may be appropriate for this site to regulate flows such that the site is allowed to fill with sediment as quickly as possible, but does not induce any changes to the local channel morphology. GUDF25W Site: Located approximately 11 river miles upstream of the Butch Craig site, the GUDF25W or Dad's Flat site offers no reasonable flooding enhancement opportunities. Also, the existing flooding frequency at the site, a 25-year event, does not make the site worthwhile for an easement to protect the habitat. Colorado River CRBR181 N Site -The CRBR181 N properties are located in the 15-mile reach just upstream of the Clifton Water Treatment Plant at 34 Road. For the BO and BR ponds, the sites provide 26 and 8 floodable acres respectively. The sites are protected by a man-made dike against Colorado River flows up to the 50-year event. Flooding enhancement could be implemented at the site by removing a 140-foot section of the dike that is not heavily vegetated. However, several mitigation measures are necessary to protect adjacent sites from flooding with increased frequency. Several alternatives have been laid out to Fish and Wildlife Service personnel. and cost estimates performed by the Bureau of Reclamation engineers and construction personnel. A brief summary of the site configuration options and mitigation measures are presented in this report. This site is a good indicator of how future floodability assessments may involve more parties, multiple design alternatives and potentially heavy costs associated that may eliminate some candidate sites. In addition to the sites presented in this report, floodability assessments have been conducted on two new Gunnison River sites near Delta, Colorado and four new Green River sites near Vernal, Utah in 1998. At the time this report was written the analyses had not been completed for these sites. Results of the aforementioned assessments should be available in early 1999.