Inyo/LA Cooperative Studies

The following are summaries of seven cooperative studies being developed or conducted by the Inyo/Los Angeles Technical Group. The full study proposals can be accessed by clicking the individual study titles.

1. Development of Hydrological Modeling Tools Robert Harrington, ICWD; Saeed Jorat, LADWP Approved by the Standing Committee, May 11, 2000. The purpose of this study is to improve hydrological models developed by previous cooperative studies to evaluate the impact of groundwater pumping, weather variations, surface water management, and other hydrologic changes on groundwater levels. Because groundwater modeling is the only method for consistent interpretation of groundwater data and evaluation of management options, this task is a prerequisite to fulfill the monitoring and technical goals of the Water Agreement. Inyo County and LADWP want to jointly develop a common set of modeling tools so that methods and analyses are understood and accessible to each agency.

2. Evapotranspiration from Groundwater-Dependent Plant Communities: Comparison of Micrometeorological Measurements and Vegetation-based Measurements Robert Harrington, Aaron Steinwand, ICWD; Paula Hubbard, David Martin, LADWP Approved by Standing Committee, March 23, 2000.             See proposal here             See final report here (2.5MB, September 15, 2004)

3. Characterization of Confining Layer Hydrologic Conductivity and Storage Properties in the Owens Valley Randy Jackson, ICWD; Saeed Jorat, LADWP Approved by Standing Committee March 23, 2000. The purpose of this study is to determine confining layer hydrologic properties to assist groundwater modeling efforts (study #1) and to improve the management of wells sealed to the deep aquifer. Pumping from deep aquifers potentially could be managed differently than the Green Book methods. Without information to be developed by this study, however, the magnitude and timing of the water table drawdown from pumping deep aquifers are difficult to predict, complicating any assessment of the effects of different pumping scenarios. A stepwise approach is proposed, starting with analysis of existing data and progressing to low and high intensity field projects, if necessary.

4. Shallow and Deep Groundwater Geochemistry and the Source of Spring and Seep Water in the Owens Valley Aaron Steinwand, Randy Jackson, ICWD; Saeed Jorat, Paula Hubbard, LADWP Approved by Standing Committee            See proposal here            See final report here

5. Application of Canonical Community Ordination (CANOCO) to Assess Vegetation Change  Sally Manning, ICWD; David Martin, LADWP Approved by Standing Committee March 23, 2000. This study proposed to apply complex statistical techniques to an extensive dataset of vegetation measurements collected by ICWD vegetation staff to quantify the importance of several environmental factors, such as water table fluctuations, influencing vegetation changes observed in the last decade. Since 2000, the principal investigators have worked independently to investigate factors influencing Owens Valley vegetation change. After working with the data at hand, Dr. Manning has determined that it would be preferable to substitute multiple linear regression as the analytical method. Results of analyses performed to date have been documented in written reports, presented by Dr. Manning at conferences and other presentations, and incorporated into manuscripts.

6. Inventory and Classification of Riparian Vegetation in the Owens Valley for Use in Future Monitoring Sally Manning, ICWD; David Martin, LADWP; and unnamed consultant Approved by Standing Committee March 23, 2000. The objective of this study is to inventory, map, and classify riparian (Type D) vegetation on Los Angeles-owned land in Owens Valley to improve monitoring and management of these areas. This study was suggested in the Green Book (the technical appendix to the Water Agreement) but has not been completed. The Standing Committee agreed at its March 23, 2000, meeting that this work will be conducted by a consultant selected jointly by ICWD and LADWP, and the contract will be managed by LADWP. Work was to begin in March 2001. At present, LADWP is reviewing a draft request for proposals and a tentative map outlining of areas to be inventoried.

7. Development of a Demographic Model for Nevada saltbush (Atriplex torreyi) Sally Manning, ICWD; David Martin, LADWP, Consultant to be funded by LADWP Approved by Standing Committee March 23, 2000. The purpose of this study is to use existing data for Nevada saltbush collected by ICWD vegetation staff to develop a model that could allow researchers and managers to make predictions about future population trends of this species. Nevada saltbush is a native shrub that commonly invades meadows subjected to pumping. It has the potential to out-compete grass species and change the character of the plant community in a way not allowed under the Water Agreement. It is unclear whether, once begun, saltbush invasion can be halted and whether existing saltbush-dominated communities are sustainable. A consultant to assist with the modeling work has not been selected. Since 2000, the principal investigators have worked independently on this study. Water Department staff continue to collect field data annually, and Dr. Manning recently completed a preliminary report analyzing the fate of some saltbush recruits.