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<br />10995 t <br /> <br />ENGBR <br />824.02(Purgatoire (Picket Wire) River, Colorado) <br />Subject: Purgatoire River, Colorado <br /> <br />has decreased in the last several decades but it is now believed to have <br />stabilized. Precipitation averages 16.8 inches annually at Trinidad and <br />22.3 inches at North Lake in the mountainous headwaters. <br /> <br />3. The basin is subject to destructive floods. Within the area <br />under consideration, damage is largely concentrated in the 39-mile reach <br />between mile 161, about 4 miles above Trinidad, and San Francisco Creek. <br />Seven major and numerous lesser floods have occurred within this reach <br />since 1866. The maximum recorded flood occurred on 30 September 1904 <br />with a discharge of 45,400 cubic feet per second at Trinidad. This flood <br />affected 370 acres of urban residential, business, railroad and industrial <br />properties, and 4,580 acres of rural lands. The estimated value of prop- <br />erty that would be inundated by a recurrence of the 1904 flood is $8,801,000 <br />of which $561,000 is for agricultural lands and facilities, $6,029,000 for <br />transportation facilities and utilities, and $2,211,000 for urban property. <br />Damages which would be caused by such a flood are estimated at $1,907,000. <br />Average annual flood damages with the present state of development are <br />estimated at $226, 700. <br /> <br />4. Irrigation improvements are largely concentrated in the Sunflower <br />Valley and Model areas between Trinidad and San Francisco Creek. About <br />19,500 acres are presently irrigated within this reach. Irrigation storage <br />reservoirs consist of Model Reservoir on Chicosa Creek with a usable capac- <br />ity of less than 10,000 acre-feet and a storage right of 20,000 acre-feet, <br />and Johns Lake with a storage right of 345 acre-feet, which has not been <br />used for many years. Several smalJ reservoirs for municipal water supply <br />are loca~ed in the upper basin. The flow of Purgatoire River through <br />Trinidad', consists of a relatively low base flow, spring runoff from snow- <br />melt, ahd flows from intense summer storms. The average annual discharge <br />at Trinidad for the period 1925 to 1949 is 65,100 acre-feet. Of this <br />flow, an average of 54,000 acre-feet annually has been divprted for irri- <br />~ation use and an additional 500 acre-feet diverted from r.hi~n~~ r.r~~k <br />