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I CHANGES ARE MADE IN DETERMINATIONS OF BASE FLOOD ELEVATIONS FOR TIIE CITY OF BOULDER, BOULDER COUNTY, COLORADO, UNDER TIIE NATIONAL FLOOD INSURANCE PROGRAM On June 2, 1995, the Department of Homeland Security's Federal Emergency Management Agency identified Special Flood Hazard Areas (SFHAs) in the City of Boulder, Boulder County, Colorado, through issuance of a Flood Insurance Rate Map (FIRM). The Mitigation Division has determined that modificatidn ofthe elevations of the flood having a I-percent chance of being equaled or exceeded in any given year (base flood) for certain locations in this community is appropriate. The modified Base Flood Elevations (BFEs) revise the FIRM for the community. The changes are being made pursuant to Section 206 of the Flood Disaster Protection Act of 1973 (Public Law 93-234) and are in accordance with the National Flood Insurance Act of 1968, as amended (TitJeXIll of the Housing and Urban Development Act of 1968, Public Law 90-448), 42 U.S.C. 4001-4128, and 44 CFR Part 65. A revised hydraulic analysis was performed to incorporate channel improvements along Goose Creek from 30th Street to approximately 1,900 feet upstream of Folsom Street. These channel improvements also affected Eimers Twomile Creek from the confluence with Goose Creek to approximately 260 feet downstream of Valmont Drive. lbi.s has resulted in a revised delineation of the regulatory floodway for Goose Creek; a decrease in SFHA width and decreasc:;d BFEs for both Goose Creek and EImers Twomile Creek; and an increase in SFHA width for a shallow flooding area adjacent to Eimers Twomile Creek from approximately 330 feet downstream of Valmont Drive to the Goose Creek floodplain boundary. The aforementioned channelized portion of Goose Creek contains the base flood. The table below indicates existing and modified BFEs for selected locations along the affected lengths of the flooding source(s) cited above. Existing BFE Modified BFE Location (feet) (feet) Goose Creek: Approximately 380 feet upstream of 30th Street 5,276. 5,273. Approximately 150 feet upstream of confluence with Eimers Twomile Creek 5,316. 5,315. Eimers Twomile Creek: Approximately 650 feet downstream ofValmont Drive 5,294. 5,288. Approximately 330 feet downstream ofValmont Drive 5,295. 5,294. Shallow Flooding Area: Approximately 650 feet downstream ofValmont Drive 5,294 · I" Approximately 330 feet downstream ofValmont Drive 5,295. I" .National Geodetic Vertical Datum, rounded to nearest whole foot "Depth above ground, rounded to nearest whole foot Under the above-mentioned Acts of 1968 and 1973, the Mitigation Division must develop criteria for floodplain management. To participate in the National Flood Insurance Program (NFIP), the community must use the modified BFEs to administer the floodplain management measures of the NFIP. These modified BFEs will also be used to calculate the appropriate flood insurance premium rates for new buildings and their contents and for the second layer of insurance on existing buildings and contents.