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. . . PREFACE This Floodplain Information Report (FIR) is part of a program by the Colorado Water Conservation Board (CWCB) to make approximate floodplain maps prepared by the Federal Emergeney Management Ageney (FEMA) easier for local governments to use. This CWCB report provides limited engineering information to revise the federal maps, if neeessary, and to support the approximate delineations on the maps, and it provides floodplain management information to guide the loeal governments in the use of the maps. The offieial floodplain information for the Town of Otis is the Flood Hazard Boundary Map (FHBM) dated September 26, 1978, whieh was subsequently eonverted to a Flood Insuranee Rate Map (FIRM), dated August 19, 1985. Neither the FHBM nor the FIRM has any published engineering information aeeompanying it to deseribe the engineering basis of the maps or the manner in whieh the town eould use it for floodplain management. In addition, the FIRM eontains approximate floodplain delineations that are outdated beeause of inaeeurate eorporate limits and beeause of the eompletion of a flood eontrol projeet after the date of the FIRM, August 19, 1985. The initial purpose of this report, therefore, is to provide the town both with revised approximate floodplain delineations and with limited supporting information for those approximate delineations. The report includes a deseription of a hydrologie analysis that was performed for the town as part of a state-funded master drainage and floodplain study, prepared after the date of the FIRM. The CWCB has ensured that the hydrologie analysis is eonsistent with the revised mapping. In addition to providing engineering information, the report gives the town some basie information about floodplain management and it gives some alternatives that eould be eonsidered in formulating and implementing its floodplain management objeetives. A seeond funetion of this report is to assure that the FIRM, as revised by the CWCB, meets the basie teehnieal requirements for designation and approval by the CWCR Without a report and without a hydrologie analysis, the revised FIRM eannot qualify for CWCB designation. Colorado statutes require that loeal governments obtain from the CWCB the designation and approval of floodplain information for its use in regulatory purposes. This report provides a means for the revised FIRM to meet that statutory objeetive. The FIRM was prepared prior to the eompletion of two detailed floodplain information documents prepared for the town and the CWCR The first document is a floodplain information report entitled Town of Otis Master Drainage and Flood Study, prepared by Engineering Professionals, Ine. in May 1986. The other document is a floodplain information map entitled Project Layout, Drainage and Floodplain Improvements, prepared by Norton, UndelWood & Lamb in January 1988. These two doeuments provide the neeessary hydrologie information to revise the approximate 100-year floodplain boundaries identified on the Flood Insuranee Rate Map (FIRM) and to support those revised boundaries. The hydrologie information eontained in the two detailed doeuments was used in preparing this report, including the revisions to the Otis FIRM, and it supports the subsequent designation of the revised FIRM.