Water Department
The Monitor 1998
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New Program of Cooperative Studies Aaron Steinwand, Soil Scientist/Science Coordinator Nearly a decade ago, Inyo County and Los Angeles developed the techniques for groundwater and vegetation management that became the basis for the Inyo/Los Angeles water agreement and its technical appendix, the Green Book. At the time, it was recognized that there would be a need for continuing research and cooperative studies to achieve the goals of the agreement. Consequently, the agreement was designed to be flexible to allow adoption of improved techniques. Very few studies were conducted in recent years, however, due in part to litigation over the 1991 environmental impact report for groundwater management in the Owens Valley. Also, during the recent drought, the Green Book's methods were superceded by the goals and conservative management provisions of the Drought Recovery Policy.
The litigation ended in 1997, and the effects of the drought are diminishing in many areas of the valley. The Inyo/Los Angeles Technical Group, therefore, determined it was timely and appropriate to undertake a cooperative study program to investigate several areas of concern regarding the Green Book's methods for managing groundwater pumping. At its June 1998 meeting, the Inyo/Los Angeles Standing Committee concurred and directed the Technical Group to design studies addressing the concerns. The central question that must be answered to successfully manage groundwater pumping and achieve the goals of the water agreement is: What amount of pumping avoids adverse changes to the vegetation and provides a reliable supply of water for Inyo and Los Angeles? To answer that question, the natural environment must be understood. Briefly, the underlying assumption about the Owens Valley environment is that vegetation conditions are substantially influenced by water table depth and fluctuations. This assumption is supported by multiple lines of evidence that will not be described here. Thus, to include the critical variables affecting the vegetation, pumping decisions should consider the expected water table drawdown and the vegetations tolerance to water table fluctuations. To accomplish this, the studies proposed by the Inyo County Water Department's scientific staff were directed specifically at improving the tools used to predict the effect of pumping on the water table and at quantifying how Owens Valley plant communities respond when several environmental factors change simultaneously, including water level fluctuations caused by pumping. ICWD has proposed the following studies to improve the methods for managing groundwater in the Owens Valley. Development of Hydrological Modeling Tools Development of a Model for Predicting Plant Water Use and Soil Water Replenishment |
