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MONO LAKE: A LESSON IN ENVIRONMENTAL PROBLEM SOLVING Mono Lake is one of the oldest lakes in North America. Located in the high desert on the eastern slope of the Sierra Nevada Mountains, it is a strangely beautiful salt lake. Tufa towers - large deposits of calcium carbonate - are located on its shores and protrude from its surface. The lake's salinity (over twice that of ocean water) is a result of thousands of years of evaporation concentration. As a consequence of its chemistry and high salinity; no fish live in Mono Lake and the food chain is simple. Brine shrimp and brine flies feed on algae, and five species of birds feed on the shrimp and flies. In 1941, metropolitan Los Angeles began to divert fresh water from the streams that flow into the lake. By the late 1980's, these diversions provided 17 percent of the city's water supply by diverting all the water from all the streams that flowed into the lake. Largely as a result of these diversions, the surface elevation of the lake dropped, its volume and surface area decreased, and the salinity of the lake doubled. Under a special bill passed by the California legislature, Dr. Daniel B. Botkin, founder of CSE, directed a study concerning "the effects of water diversions on the Mono Lake ecosystem". A report summarizing the results of the study entitled The Future of Mono Lake was published in 1988. Critical Lake Levels for Management The study found that because the physical, geological, and biological components of Mono Lake are relatively few and are rather tightly bound together, the consequences of further reductions in lake level and volume could be predicted with unusual certainty. If stream diversions continued at the maximum rate permitted in 1988 (90,000 acre feet per year) a significant impact could be realized as soon as 1989 when the dropping lake level would expose a land bridge between the shoreline and an island that serves as a major bird breeding area, providing access to the island of predators such as coyotes. Coyotes eat eggs and chicks, and disrupt bird breeding behavior. Furthermore, the study predicted that by 1994, an important geological change would occur in the lakebed slope when the "topographic nick point" would be exposed. At this point, the lake would be at its lowest level since the last ice age. Once the lake dropped below that level, erosion would increase, increasing damage to the tufa towers. A third major consequence would be realized by 1999 when the decline of the lake level and associated reductions in its volume would raise salinity to the point where the productivity of the brine shrimp would begin to decline. Finally, the existing lake ecosystem could cease to function by 2012 when lake salinities would reach levels at which brine shrimp and brine flies could no longer survive, thus depriving 1.3 million birds of their food source at the lake. If both modern climatic conditions and historical rates of diversion continued, the lake would reach a level some 31 to 48 feet below the 1988 level. This would be considerably below the level that could support the current lake ecosystem. The lake would die. The report stated that if the streams flowing into Mono Lake were to be managed to avoid these consequences, it would be necessary to identify not only those lake levels at which critical changes occurred but also the buffer levels that would have to be maintained to prevent the lake from falling below these critical levels as a consequence of normal climatic variation. The buffer level was a new idea and one that many people found hard to understand. The concept is that if the lake were at the "buffer" level during an average rainfall year, then when a once-in-fifty year drought comes, the lake level would decline just to, but not below, the minimum acceptable level. Three key buffer levels were identified: At Level I, 6382 feet above sea level, major features of the lake ecosystem and most scenic attributes would be protected, although there would be some erosion of the tufa towers. At Level II, 6372 feet, a large portion of the California gull breeding habitat would be lost, a significant number of tufa towers would be endangered, the breeding biology of the snowy plover would be endangered, and a portion of existing wetlands would be threatened with drainage. The production of brine flies and brine shrimp would, however, be maintained. At Level III, 6362 feet, the lake would become unreliable as a staging and breeding area for birds. This level would provide a 10 foot buffer above the critical level of 6352 'feet at which the lake ecosystem would be fundamentally altered. At this level, the production of brine flies and brine shrimp would be reduced to the point where bird populations could no longer be supported. Why Were Ecologists Able to Answer with Greater Certainty than Usual? One reason had to do with the way the evaluation was conducted. By funding field researchers to analyze and report existing results rather than conduct more research, the researchers were able to bring together information that was previously not available. The panel integrated this information and was able to bring the data to bear objectively on a few sharply focused questions. Finally, by developing alternative scenarios of lake level effects, the panel avoided dealing directly with value judgments. Another reason had to do with the nature of the Mono Lake ecosystem itself. Its high salinity supports a simple food web. Rather than dealing with hundreds of animal species, the panel was able to focus on seven. Also, the source of the environmental disturbance was clear and its consequences were simple and direct. Finally, because the major interactions occur in an aquatic environment with no stream outlet, they could be more easily measured and are less subject to the effects of events beyond the boundaries than is generally the case. Resolution of the Issue After the publication of "The Future of Mono Lake," a mediation process ensued. One significant result of the report was that there was a reversal in judicial decision regarding Mono Lake and the City of Los Angeles. Prior to this report, a judge had determined that the city could continue to divert water unless it was shown that this diversion had a negative environmental effect. After the publication of the report, the judge reversed the decision. The lake had to be returned to the highest of the three levels identified in the report, unless the city could show that any lower level would have no negative environmental effect. The panel had provided a clear statement for policy makers regarding the consequences of varying the amount of water diverted. The panel did not try to make policy, but instead explained to the public what options were possible. In the fall of 1994, the City of Los Angeles gave up all claim on water inflows to Mono Lake. Since that time, the lake level has begun slowly to rise. |
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