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Study Areas

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• Alexander Valley
• Santa Rosa Plain
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Location of Santa Rosa Plain, CA

Santa Rosa Plain

The Santa Rosa Plain, home to approximately half of the population of Sonoma County, faces growth in population and demand for water. Water supply is provided by a combination of ground water and water delivered via aqueduct from the Russian River. Water managers face the challenge of meeting the increasing water demand with a combination of Russian River water, which has uncertainties in its future availability, and local ground-water resources. The water use decisions by the different entities in the Santa Rosa Plain will have an impact on other ground-water users.

The two overarching ground-water management questions in the Santa Plain are:

1. What will be the effects of future ground-water development in the Santa Rosa Plain? In particular, the increase in ground-water demand resulting from urban growth and other land use changes will affect water levels, recharge, surface-water discharge, and water quality. Current regional water-quality concerns in the Santa Rosa Plain include iron, manganese, and arsenic. There also is localized contamination from volatile organics such as PCE. Increasing ground-water development may also induce land subsidence.
2. What are efficient strategies for surface-water/ground-water management that will assure the long-term viability of water supply in the Santa Rosa Plain? Historically, individual ground-water users in the Santa Rosa Plain—municipal, agricultural, and domestic—have proceeded independently in their utilization of ground water. As pumpage has increased, it is becoming clear that changes in pumpage in one location can have impacts on ground-water conditions elsewhere in the basin. Similarly, Russian River water and ground water have historically been used as separate sources of supply, but not explicitly managed in a linked manner. The increasing water demand, potential reduction in availability of Russian River water, likely lowering of some maximum contaminant limits (MCLs), and increasing environmental awareness in the region, make integrated surface-water/ground-water management essential. Management strategies may include aquifer storage and recovery (ASR) projects. ASR projects could be operated on a seasonal basis to capture surplus winter flows or on a multi-year climatic basis to store water for drought protection.

Approach: The primary objectives of this second phase of the program are to: 1) develop an updated assessment of the geohydrology and geochemistry of the Santa Rosa Plain; 2) develop a multi-aquifer ground-water flow model for Santa Rosa Plain; and 3) evaluate the hydrologic impacts of alternative ground-water management strategies for the basin.

Project Status: Fiscal Year 2006 Progress Report for the Santa Rosa Plain project.

Stakeholders: Sonoma County Water Agency, City of Santa Rosa, City of Rohnert Park, City of Sebastapol, City of Cotati, Town of Windsor, and California American Water.

For additional information:
Project Chief: Tracy Nishikawa
Program Chief: Eric Reichard