| OCR Text |
Show to regulate the pond's surface level between 4215 and 4217 feet and the return of concentrated brine to the lake. Return flow through the military range was not confined and flowed over the natural topography in an expansive path on its return to the lake. Pumping started on April 10, 1987 and continued until June 30, 1989. During this period an estimated 2.73 million acre- feet of brines were pumped from the lake. The pumping was started too late to have a significant impact on the maximum lake level in 1987; however, the pumping project was successful in increasing the rate of decline of the lake and lowering the level of the lake some 15 inches. After pumping had ceased, the lake level continued to drop an additional two feet through the end of 1989. Precipitation dropped to average levels or below. The lake level continued to drop an additional four feet through the end of 1993. Operating Consequences and Constraints The design of the WDPP was modified prior to construction. The original design called for brine to be pumped from the fresher south arm of GSL. The final modification reduced the cost of the project and sped construction by pumping brine from the north arm. The use of more concentrated north arm brine reduced the evaporation potential of the project and resulted in more salt being left in the West Pond. In 1994, USGS published a report entitled " Salt Budget of the West Pond, Utah, April 1987 to June 1989." The report summarized the salt budget as follows: " During operation of the West Desert pumping project, April 10, 1987, to June 30, 1989, data were collected as part of a monitoring program to evaluate the effects of pumping brine from GSL into West Pond in northern Utah. The removal of brine from GSL was part of an effort to lower the level of GSL when the water level was at a high in 1986. These data were used to prepare a salt budget that indicates about 695 million tons of salt or about 14.2 percent of salt contained in GSL was pumped into West Pond. Of the 695 million tons of salt pumped into West Pond, 315 million tons ( 45 percent) were dissolved in the pond, 71 million tons ( 10.2 percent) formed a salt crust at the bottom of the pond, 10 million tons ( 1.4 percent) infiltrated the subsurface areas inundated by storage in the pond, 88 million tons ( 12.7 percent) were withdrawn by Magnesium Corporation of American ( Magcorp), and 123 million tons ( 17.7 percent) discharged from the pond through the Newfoundland Weir. About 88 million tons ( 13 percent) of the salt pumped from the lake could not be accounted for in the salt budget. About 94 million tons of salt ( 1.9 percent of the total salt in GSL) flowed back to Great Salt Lake." Therefore at the end of pumping operations, approximately 484 million tons of salts were either in the pond or infiltrated into the subsurface. Another 211 million tons were withdrawn by Magcorp or discharged over the Newfoundland Weir. About 94 million tons of the 211 million tons had returned to the lake. Therefore approximately 600 million tons ( as of 1989) had been pumped but not returned to the lake. Efforts are underway to estimate how much additional salt has returned to the lake since 1989. 34 |
