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<br />January 7, 2004 20 <br />Reclamation is the lead agency in the Native fish Work Group, a multiagency group of scientists <br />attempting to augment the ageing stock of the endangered razorback sucker in Lake Mohave. Larval <br />razorback suckers are captured by hand in and around spawning areas in late winter and early spring <br />for rearing at Willow Beach Fish Hatchery below Hoover Dam. The following year, one year old <br />razorback suckers are placed into predator-free, lake-side backwaters for rearing through the spring <br />and summer. When the lake is normally drawn down during the fall, these fish are harvested from <br />these rearing areas and then released to the lake. The razorback suckers grow very quickly, usually <br />exceeding ten inches in length by September. <br /> <br />In 2002, 10,473 razorback suckers (300 mm minimum size) were repatriated into Lake Mohave from <br />all sources. In 2003, 28,486 wild larvae were captured from natural spawning congregations on <br />Lake Mohave and delivered to Willow Beach Hatchery. <br /> <br />Senator Wash and Laguna Reservoirs <br /> <br />Operations at Senator Wash Reservoir allow regulation of water deliveries to United States and <br />Mexican water users downstream ofImperial Dam. The reservoir is utilized as an off-stream storage <br />facility to meet downstream water demands and to conserve water for future uses in the United <br />States and the scheduled uses of Mexico in accordance with Treaty obligations. Senator Wash <br />Reservoir is the only major storage facility below Parker Dam (approximately 142 river miles <br />downstream) and has storage capacity of 13,836 acre-feet at full pool elevation of251 feet, mean sea <br />level. Operational objectives are to store excess flows from the river which have been caused by <br />water user cutbacks and side wash inflows due to rain. Stored waters are utilized to meet irrigation <br />and Treaty demands. <br /> <br />Elevation restrictions on Senator Wash Reservoir reduce the flexibility of water storage in the lower <br />reaches of the river. In August of 1992, a restrictionat elevation 240 feet, mean sea level, (9,144 <br />acre- feet of storage) at Senator Wash Reservoir was put in place. This was due to potential piping <br />and liquefaction of foundation and embankment materials at West Squaw Lake Dike and Senator <br />Wash Dam. A filter blanket at West Squaw Lake dike was constructed during the first part ofCY <br />2000, and a reservoir fill test was started September 15 and concluded on October 19,2000. The <br />test had to be stopped due to piping concerns at West Squaw Lake Dike. Therefore, Senator Wash <br />was not available most of CY 2000 to regulate river flows and excess flows to Mexico exceeded <br />300,000 acre-feet for the year. After the fill test in CY 2000, a new elevation restriction at 235 feet <br />(7,330 acre-feet of storage) was put in place, and excess flows to Mexico were reduced to about <br />200,000 AF in CY 2001. In CY 2002 a permanent filter blanket was placed at West Squaw Lake <br />Dike, additional instrumentation was put in place, and another fill test was conducted from April <br />through July 7,2002. Senator Wash was not available for river regulation essentially from the first <br />ofCY 2002 until July 7, 2002. Due to the success of this fill test, the elevation restriction was raised <br />back to elevation 240 feet on July 8, 2002. The Denver Technical Service Center is currently <br />reviewing data from the test to determine if operations will be allowed to exceed elevation 240 feet. <br /> <br />Total overdelivery to Mexico for CY 2002 was approximately 133,000 AF. As of September 2003, <br />overdeliveries to Mexico have been about 55,400 AF and are expected to be about 60,000 AF for the <br />year, subject to the amount of rain received. Overdeliveries in CY 2003 have been primarily due to <br /> <br />