The Sonoma County Water Agency's water supply is constrained by limits on its withdrawals from the Russian River and by its surface water storage capacity. The Agency's 2005 Urban Water Management Plan (UWMP) assumes that the Agency will expand its rights to withdraw water from the Russian River by 2016 in order to meet projected increases in water demand. However, the Agency is not currently pursuing plans to expand its water rights, and such an expansion might be difficult given various regulatory limitations on the Russian River. Without increased supply, projections in the 2005 UWMP suggest that the by 2020 the Agency's supply will fall 13,166 ac-ft short of its contractors' demand for water.
In addressing projected shortfalls, SCWA's options are limited by its need to raise enough revenue to cover both its fixed and variable costs. The Agency is also constrained by being a water wholesaler; it does not interact directly with the end users of water.
The most cost-effective solution to addressing projected water deficits will likely involve both supply expansion and demand reduction. This report analyzes demand reduction options that the Agency could pursue. Further analysis would be necessary to determine to what extent projected water shortfalls can be addressed through supply expansion and what the most cost effective mix of supply expansion and demand reduction is. Reducing water demand has the additional benefit of reducing energy required to pump and treat water, which will help SCWA meet its goal of making its water supply and transmission system operations carbon-free.
In order to continue operating during a 2009 drought, SCWA obtained permission from the State Water Resources Control Board (SCWRB) to reduce downstream Russian River flows below normally allowable levels. As part of the agreement with the SCWRB, the Agency reduced its diversions from the Russian River by over 25% through conservation programs and increased use of local supply. However, having less water to sell resulted in a significant revenue loss for the Agency. While long-term conservation can reduce the frequency and severity of short term supply shortages by reducing baseline water use and maintaining higher storage levels, they will still likely occur.