Annual Operating Plan For Colorado River Reservoirs 2004

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January 7, 2004 21 In 2002,10,473 razorback suckers (300 mm minimum size) were repatriated into Lake Mohave from ' all sources. In 2003, 28,486 wild larvae were captured from natural spawning congregations on Lake Mohave and delivered to Willow Beach Hatchery. Senator Wash and Laguna Reservoirs Operations at Senator Wash Reservoir allow regulation of water deliveries to United States and Mexican water users downstream of Imperial Dam. The reservoir is utilized as an off - stream storage facility to meet downstream water demands and to conserve water for future uses in the United States ' and the scheduled uses of Mexico in accordance with Treaty obligations. Senator Wash Reservoir is the only major storage facility below Parker Dam (approximately 142 river miles downstream) and has storage capacity of 13,836 acre -feet at full pool elevation of 251 feet, mean sea level. ' Operational obj ectives are to store excess flows from the river which have been caused by water user cutbacks and side wash inflows due to rain. Stored waters are utilized to meet irrigation and Treaty Idemands. Elevation restrictions on Senator Wash Reservoir reduce the flexibility of water storage in the lower ' reaches of the river. In August of 1992, a restriction at elevation 240 feet, mean sea level, (9,144 acre -feet of storage) at Senator Wash Reservoir was put in place. This was due to potential piping and liquefaction of foundation and embankment materials at West Squaw Lake Dike and Senator Wash Dam. A filter blanket at West Squaw Lake dike was constructed during the first part of CY 2000, and a reservoir fill test was started September 15 and concluded on October 19, 2000. The test had to be stopped due to piping concerns at West Squaw Lake Dike. Therefore, Senator Wash ' was not available most of CY 2000 to regulate river flows and excess flows to Mexico exceeded 300,000 acre -feet for the year. After the fill test in CY 2000, a new elevation restriction at 235 feet (7,330 acre -feet of storage) was put in place, and excess flows to Mexico were reduced to about 200,000 AF in CY 2001. In CY 2002 a permanent filter blanket was placed at West Squaw Lake Dike, additional instrumentation was put in place, and another fill test was conducted from April through July 7, 2002. Senator Wash was not available for river regulation essentially from the first of CY 2002 until July 7, 2002. Due to the success of this fill test, the elevation restriction was raised back to elevation 240 feet on July 8, 2002. The Denver Technical Service Center is currently reviewing data from the test to determine if operations will be allowed to exceed elevation 240 feet. Total overdelivery to Mexico for CY 2002 was approximately 133,000 AF. As of September 2003, ' overdeliveries to Mexico have been about 55,400 AF and are expected to be about 60,000 AF for the year, subject to the amount of rain received. Overdeliveries in CY 2003 have been primarily due to rejected water caused by rain in January, February, March and April. To further improve control of ' the deliveries of water from Parker Dam, Senator Wash will be operated at a lower elevation (below the minimum power pool) to capture additional excess flows at Imperial Dam. Improvements to the river routing software used to schedule the releases from Parker Dam may also reduce the uncertainty ' in the flows arriving at Imperial Dam. Other storage options are also being investigated, primarily the proposed construction of reservoir storage near the All American Canal.