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.. ...... ,~ ,-. 1 / .j t. The investigators considered several alternative me~s of co~trolling the geyser. Plugging of the geyser was one alternat~ve cons~dered, but this was abandoned because the geologic conditions ~t the geyser are such that the rising saline water would simply erupt at other locations in the immediate vicinity. The alternative recommended by the investigators, and to be authorized by the legislation, would be to construct a dike around the points of eruption that would capture the erupted water. A portion of the erupted water would return to the geyser and the remainder would be conveyed by gravity through a pipeline about three miles to a 40 acre evaporation pond. The control plan would prevent the entire annual 3,000 tons of salt from entering the river. The dike would be designed to blend with the exposed sandstone formation for esthetic purposes. Because of the return of a portion of the erupted water to the geyser, the interval between eruptions will be reduced from 5-6 hours to 2-3 hours, increasing its value as a tourist attraction. The estimated cost of the proposed project would be $~90,000 with an annual operation, maintenance and replacement cost of $3,000. As construction would be completed in less than a year, the project's capital cost is the same as the construction cost, and, amortized at 100 years and 6 7/8 percent interest rate, the annual capital and operating costs would amount to $30,000. The salinity impact at Imperial Dam of removing 3,000 tons per year of salt by the project would be an 0.3 ppm reduction in the year 2000. Las Vegas Wash is a natural channel which drains from the Las Vegas Valley into the Las Vegas Bay arm of Lake rljead. Historically, Las Vegas \'lash was an intermittent stream flowing only during periods of high rainfall and runoff. Vith the expansion of Las Vegas, effluent from municipal and industrial waste treatment plants was discharged into the Hash and this, along with rising water from ground water flows, has created a perennial flow into Lake Mead. The Wash adds about 209,000 tons of dissolved solids annually tJ the Colorado River system. The sources are both point and diffuse. The point sources, effluent from sewage treatment plants with secondary treatment and power plant cooling water blowdown, account for about 20 percent of the total salt load. The remaining 80 per- cent of the salt load comes from rising ground water, a diffuse source that includes flows from a long established groundwater mound e beneath industrial waste ponds, and regional groundlV'ater discharge flows. A program to renovate the industrial waste ponds is now underway, and impervious linings will be installed that will prevent ~ the continued percolation of the saline wastes from the Basic Manage- ment, Incorporated industrial complex near Henderson, Nevada. These facilities were built by the Federal Government and operated under its control for many years. - 18 -