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H'iDROWGIC A~ll H'iDRAL'lIC DETERMINATIONS STUDY AREA DESCRIPTION Flood History Drainage Basin CharacteristiCs Very high streamflo~s were experienced in Willow Creek at Creede during the following years, 1911, 1921, 1927, 1941, 1948, and 1949. These exceedingly high flows prompted the U.S. Army Corps of Engineers to design and construct a concrete flood control channel through town (completed in 1950). According to the Corps of Engineers (Refs. 8 and 11), in October of 1911, folloO'1.ng t~o days of heavy rain, the wooden flume that was in existence at that time ran full. Other times that the wooden flum" ran full, according to the Corps,wereinl921,Juneof 1927, and May of 1941. Estimates of the peak strea",flo~s by the Corps for these events were based on the estimated flun>e capacity on those dates (capacity varied due to damage to the wooden flume). The Corps estimates of peak flows and the event types are given as follo~s: Willow Creek headwaters are located along the Continental Divide with the highest point in the basin being at 13,718 fcet (~Garita). The northern town boundary of Creede is at elevation 8870 feet, East and West Willow Creeks combine to for", l<Iillo" Creek approximately 0.6 miles north of the northern corporate limit of Creede, Both creeks flow through and by several abandoned mines. The drainage area of l<Iillow Creek at the northern corporate limit is 35.3 square miles (see Basin Map, Plate 1). Estimated Year Peak Flow Event~ -rcfsr-- 1911 1800 Rain 1921 1400 Snow 1927 1400 Rain on sn01< 1941 1400 Snow 1948 noo Sno.~ 1949 1300 Snow Study Reach DescriPtion The study reach along l<Iillow Creek coverS the area "ithin and nearby the Town of Creed~'s corporate li",its. The length of the study reach is just over 1,0 mile. The entire length of Willow Creek through town (except the most upstream 100 feet) has been channelize~ by the Army Corps of Engineers. (See Plate 2 for Plan snd Sections). There are not many accounts of ~amage to Creede due to flooding because of protection by the flume. However, damage caused to the wooden flume during the 1941 and 1948 events allowed flood waterS to escape, causing SOllie flood ~amages to occur at residences in town (Ret. 5). According to the Corps of Engineers (Ref. 18), three lives were lost from 1905 to 1910 on account of flood1.ng, although no account of the flood events were given. The study reach was included in the Federal Insurance .\.dministration'sFloodHazardBoundaryMap (FHBM) for the Town of Creeds (Con:munity lIo. 080118A, map revised January 16, 1976), The FHBM is shown in Exhibit 2. The FHB.'1 ...as derived uaing approximate methods. Apparent1y the effects of the Corps of Engineers channel on the lOO-year floodplain were not included in this approximate study. A U.S. Geological Survey streamflow recording gage (08216500) "'NiIlow Creek at Creede" ~as put in place in 1950 at the very upstream end of the Corps of Engineers flood control channel. The highest flow recorded by this gage during its period of record (water years 1951 to 1982) was only 4JOcubic feet per second. No flooding occured in town as a re~ult of this flow. Flood Characteristics Flooding from Willow Creek is usually caused by snowmelt runoff evidenced bv an analysis of the records ef the streamflowrecordinil. "Willow Creek at Creede;'. Each of the 32 annual peaks recorded at- gage was a result of snowmelt runoff. H01<ever, rainfall runoff or on Snow runoff can occur and cause high streamflows as eVidenced by flood of October, 1911. "' Rail.e this rain <h, - , ,