Cristina Goulart, Environmental Program Manager
2025 Urban Water Management Plan Update
Adopt a resolution adopting the 2025 Urban Water Management Plan and adopting the 2025 Water Shortage Contingency Plan.
The recommended action supports the goal of Infrastructure. Goal Statement: Through a lens of sustainability and innovation, invest in the Town's infrastructure and public facilities to meet the needs of future generations.
Each urban water purveyor serving more than 3,000 connections or 3,000 acre-feet of potable water annually is required by the State of California Urban Water Management Planning Act to prepare and submit to the State an Urban Water Management Plan (“Plan”) every five years. The Windsor Water District (“District”) is an urban water supplier with 9,488 potable water connections (as of the end of 2025). The first District Plan was adopted in 1990. The official water purveyor is the District, therefore staff requests consideration of a District Board’s resolution adopting the Plan. Upon adoption, the 2025 Urban Water Management Plan will supersede the existing 2020 Plan.
The 2025 Plan also includes an updated draft of the Water Shortage Contingency Plan, a State-required element of the Plan (see Appendix F in the 2025 Plan). The draft Water Shortage Contingency Plan details how the District would respond to a reduction of up to 50 percent of available water supply.
The District’s water supply is primarily obtained from the Russian River. The majority is obtained from the District-owned Russian River Well Field, which diverts underflow from the Russian River under a Sonoma County Water Agency (Sonoma Water) water rights permit. Additionally, the District purchases water from Sonoma Water which is delivered through the Santa Rosa Aqueduct. In 2025, the District diverted 2,465 acre-feet (AF) through the RRWF and another 521 AF through the Santa Rosa Aqueduct for a total of 2,986 AF. The RRWF water is delivered primarily within the Town boundaries and Mayacama while the water purchased and delivered through the Aqueduct is primarily delivered to the outside service areas of the Airport, Shiloh, and the customers collectively known as the Outside 8.
The Plan serves as a long-range planning document for the District's water supply and has been coordinated with the wholesale water supplier, Sonoma Water. The 2025 Plan's water demand projections were developed using projections consistent with the Association of Bay Area Government's (ABAG) population and employment growth projections for our water service area and also with the Town's existing 2040 General Plan. The adopted 2025 Plan is intended to provide sound planning for the efficient management of water resources in the District’s water service area.
The 2025 Plan was developed with a distinction made between in-town water supply and demand and outside service area water supply and demand. In the past, the District’s UWMPs have treated the water demand projections and water supplies together. Dividing out water demand and supply comparisons distinctly according to the areas which receive water from different supply sources is a more accurate way to evaluate water demand projections and potential water supply deficits especially as the Town and the Airport Area move closer to build-out conditions. The Plan’s conclusions are described below separately for in-town versus outside areas.
Conclusions
In Town
The 2025 Plan concludes that, in normal supply conditions, multi-year drought scenarios, and in single-dry year scenarios, within the Town boundaries and service area served by the Russian River Well Field, there will be adequate supplies for the currently planned development out to 2050.
Outside Service Area
The conclusions for the outside service areas, served by the Santa Rosa aqueduct, are that, with the currently planned developments in various stages of the development pipeline, and with the planned development encouraged by the 2019 Airport Area Specific Plan, there are water supply shortages projected in normal, single-dry and multi-dry scenarios by 2035 without additional water supplies being developed for the outside service area. These shortages range from 8% in 2035 to 19% in 2050.
In the event of a shortage, the District’s Water Shortage Contingency Plan would be implemented to impose water conservation measures in order to reduce water demand matching the supply shortfall. These could include restrictions on landscape irrigation, car washing, or other such measures.
Why is this different from 2020 conclusions?
The 2020 UWMP projected water shortages in normal water supply years as soon as 2035 and for single-dry year scenarios as early as 2030 for both in-town service areas and outside service areas. These shortages would occur if there were no additional water supplies developed, such as new off-river groundwater wells. Five years later, the 2025 UWMP has less dire projections for the in-Town areas. The reasons are as follows:
- The population of the Town’s service area decreased between 2020 and 2022. In the 2020 UWMP, it was projected that the population of the service area would increase to 33,554 by 2025. However, the service area population for the District decreased to an estimated 25,986 from a 2020 population of 28,397.
- The District’s water customers have become more efficient on a per capita basis. The State Order for a mandatory 20% reduction in diversions from the Russian River in 2021 and 2022 has had a lasting effect on District water consumption. Many District water customers implemented long-lasting water consumption reductions, such as the purchase of higher-efficiency fixtures and appliances or replacement of high-water use landscape with lower-water using landscapes. Although consumption has bounced back to some degree, per capita use is still lower than it was in 2020.
The UWMP concludes that, for the County of Sonoma to fulfill its development plans for the Airport Area Specific Plan, water supply augmentation mitigation should be implemented. These mitigations include:
- Expansion of the recycled water distribution system to the Airport Area
- Development of non-potable groundwater wells for irrigation
- Development of potable water supply wells
Water Supply Resilience
The Plan recommends that the District continue its current program of development of off-river well supplies, pursue expansion of its recycled water system for urban uses where feasible, and maintain and enhance water conservation measures and programs. These measures are important for water supply resilience in case of water shortage emergencies ranging from drought to earthquake damage to supply lines, to disruption of Russian River supplies. These conclusions are similar to the conclusions made in the 2020 UWMP.
There is no direct fiscal impact associated with adoption of the 2025 Plan. Implementation of the various best management practices and water supply projects are addressed in the Council-approved operating and capital budgets.
Adoption of urban water management plans are not subject to the California Environmental Quality Act in accordance with Section 10652 of the California Water Code.