2050 Water Resources Study
Napa County, California

The Napa County 2050 Integrated Water Resources Plan (IWRP) represents several municipalities seeking to develop sustainable water supply portfolios involving surface, groundwater, and recycled water resources. The Napa County 2050 Water Resources Study combined West Yost staff’s institutional framework skills together with its technical and scientific capabilities to develop a multi-agency plan for long-term water resource management. The project required close coordination with the Water Resources Technical Advisory Committee, and coordination with a number of state and federal agencies.

West Yost has assisted multiple municipalities in the Napa Valley in water supply planning and design of water and wastewater facilities for many years. This assistance included development of water supply plans, assistance in negotiation of purchase of supplemental water supplies and water transfers, groundwater investigations, and analysis of recycled water use to supplement or “off-set” potable water demands and vineyard irrigation.

Based on this experience, West Yost was retained to assist all the valley municipalities and the county in the development of an IWRPto serve projected agricultural and municipal water demands projected through 2050. This effort included the review and evaluation of the methodology and accuracy of the planning criteria used in past studies, refinement of the estimates of Napa County’s total existing untreated (agricultural) and treated water demands, and projections of untreated and treated water demands for future demand areas, with the primary focus on agricultural areas, rural residential and M&I growth consistent with approved General Plans. West Yost quantified the yield available from each of the following sources: local surface water (existing reservoirs, direct diversion and use, and direct diversion and storage in a new or expanded reservoir), imported surface water; recycled water, and groundwater. Demands were compared with available supplies and deficits were identified during both normal and drought conditions.

Alternatives were developed and analyzed to provide the information needed by local agencies to base decisions on future expenditures for infrastructure, including improvements to the imported water system, recycled water and treated water storage and distribution facilities throughout the valley, and groundwater banking and production facilities. This work included regular contact with the Water Resources Technical Advisory Committee and coordination with a number of state and federal agencies. Our work product was the development of a long-range plan to integrate all the valley resources into an effective program that will maximize the yield from all available water resources for use in a coordinated and shared manner by all the valley urban agencies and the agricultural community.

This integrated water resource study involved a variety of agencies, including: Napa County; the cities of American Canyon, Napa, St. Helena and Calistoga; the Town of Yountville; Farm Bureau; Vintners Association; Grape Growing Association; large private landowners (such as Silverado Country Club); and others.