9385 - Laserfiche WebLink

Home Browse Search

Current Depletions Current annual water depletion of the Little Snake River within Wyoming is estimated to be 39,900 af (CWCS 1994). This depletion, approximately 9.1 % of the historical water yield, is broken down as follows: 23,300 af for irrigation, 16,500 af for transmountain diversions and 100 af for municipal use. In-basin municipal diversion is estimated at 200 af with a net result of 100 af of consumptive use. Irrigation depletions were estimated by assuming 20 inches of water application over 14,000 acres. Monthly depletion estimates are shown in Table 3 and include Cheyenne Stage II depletions (CWCS 1994). Stanford (1994) estimates that the average annual flow depletion is 48,800 af from the Little Snake or approximately 11 % of mean annual flow (428,000 af) in the river. This estimated depletion is greater than the CWCS estimate and a detailed analysis would be required to refine the actual amount. For comparison, the average depletion from the Yampa River is about 109,770 af (Stanford 1994) or approximately 10% of the mean annual flow. In Colorado, actual depletions from the mainstem Little Snake River are unknown at this time. The irrigation water rights which constitute all the potential depletion from the river in Colorado total approximately 142 cfs (4 m3/s). An additional 36 cfs (1 m3/s) in conditional rights remain to be perfected. The total potential depletion by Colorado diversion is 178 cfs (5 m3/s) from the mainstem Little Snake River. The cwes estimates that the average yearly Little Snake River flows at the Lily Gage adjusted for depletions is approximately 422,700 af. This compares with 428,000 af based on the historical record 1921 to 1984 (Q1Srien 1987). Water depletion simulation conducted by Western Water Consultants for the Wyoming Water Development Commission in 1990 used a data base through water year 1982. 16