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<br />Scenesiof past flooding in Longmont are shown in <br />Figures 2-9. The pictures were produced from the photo- <br />graphic records of The Longmont Daily Times-Call news- <br />paper. <br /> <br />2.4 Flood Protection Measures <br /> <br />I <br />There ~s little evidence of flood protection measures <br />along ~he study segment of St. Vrain Creek, except the <br />channelization between Sunset Street and the Colorado <br />and So~thern Railroad Bridge. There also exists a line <br />~ of lowilevees along the trailer park on the south side of <br />this s~gment. Three dams exist in the upper, mountain <br />segmen~s of the St. Vrain Creek. Button Rock Dam was <br />~ comple~ed on North St. Vrain Creek in 1969, 6 miles west <br />of Lyo~s near the City of Longmont, to store the munici- <br />pal water supply. It was not designed to store flood- <br />waters :but in the May of 1969 flood, it reduced the <br />magnit4de of the discharge that could have hit Longmont. <br />Both tHe Longmont Dam, located 1 mile downstream of the <br />Button !Rock Dam, and Beaver Reservoir, near the South <br />St. Vr~in Creek headwaters, have no effect on the flood <br />discha~ge in Longmont. <br />I <br />, <br /> <br />Left Hand Creek has been channelized along the segment <br />from P~ke Road (Colorado 22) to the mouth. The channel <br />from pfke Road ~o South Pratt Parkway is grass-lined and <br />flanke~ on either side by a grassed park and is designed <br />to contain a flow of about 3650 (cfs). From South Pratt <br />I <br />Parkway to the mouth of Left Hand Creek, the stream has <br />been c~annelized; however, the overbanks remain unimproved. <br />, <br />i <br />Various! structural and nonstructural improvements such <br />as gra~s or concrete-lined channels, detention ponds, <br />and ou~fall culverts have been implemented on Spring <br />Gulch iin the segment from 9th Avenue to 3rd Avenue. <br />, <br />These i~provements are inadequate to contain even the <br />10-yea~ flood discharge. <br /> <br />~ <br /> <br />9 <br /> <br /> <br />I <br /> <br />~ - ;,~,-bc~~, -~~"",<-<-c.x;.;.-. <br />