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. . . . . . . . . . . . . . . . . . . . I. . . . . . . . . . i. '. . . ,. i. :. . . ,. . . '. . . . . . . . '. . . . a e . ummary 0 a cu a e ISC ar~es Drainage lOO-year Flooding Source Drainage Area Description Area (mi2) Discharge (cfs) Lost CreeklWest Sand Creek at Adams!Weld County Line 118.17 16,000 Kiowa Creek at Adams!Weld County Line 271.19 27,600 Wolf Creek at mouth 103.80 14,700 Bijou Creek Tributary at mouth 3.03 1,500 West Bijou Creek at mouth 326.67 31,200 East Biiou Creek at mouth 607.76 46,800 Bijou Creek at AdamslMor,gan County Line 966.04 63,400 Little Muddy Creek at mouth 43.86 8,400 Muddy Creek at AdamslMorgan County Line 206.85 23, 100 West Box Elder Creek at mouth 28.65 8,600 Todd Creek, Tributary 2 at mouth (1) 0.01 Outside Bounds Todd Creek, Tributary 4 at mouth (I) 1.71 1,000 Todd Creek at mouth II) 7.31 2,100 North Tributary 7 at mouth 0.01 Outside Bounds T bl 4 S f C I I t d D' h Notes: (I) Area is currently being developed. However, the discharge was estimated because the area was not highly developed at the time of the FIS. Communities should regulate the approximate floodplains on a case-by-case basis. FEMA requires that a detailed floodplain analysis must be performed by a professional engineer and submitted by the developer or development proponent for development projects involving more 5 acres or more than 50 units (whichever is more restrictive). Hvdraulic Analvsis Hydraulic methods used for the approximate floodplain delineations shown on the Adams County FIRM panels are not available or have not been documented by FEMA. For future studies, an approximate 100-year flood elevation at a particular location on the river may be obtained by using the 100-year peak flow value (as provided in this report) in conjunction with an acceptable hydraulic analysis. Hydraulic analyses for determining 100-year water surface elevations for approximate floodplains may be performed using FEMA's Quick-2 computer program, the Corps of Engineers' HEC-2 computer program, Flowmaster, or other acceptable hydraulic methods. Channel and floodplain cross-sections may be obtained from detailed topographic mapping or from field surveys. Cross-sections obtained from USGS quadrangle maps are not advised. Floodplain Mapping The existing FIRMs for Adams County and Incorporated Areas depict areas subject to 100-year flooding based on approximate technical methods. The map does not show flood profiles, base flood elevations, or sufficient detail in order for county and municipal officials, engineers, developers, and land owners to make floodplain determinations with any certainty. The 7