Statewide conditions

We rely on a variety of data sources to evaluate the state's current and future water supply.

• Groundwater — water held in aquifers — is critical to the water cycle. 
• Surface water - precipitation, soil moisture, rivers, and streams and lowland snow are important contributors to surface water supply.
  • Mountain snow acts like a water supply reservoir as it slowly melts during spring and summer.

Snowpack is an important driver of water availability in many basins. Low snowpack from a warm winter impacts timing and quantity of water in streams and rivers for farms, fish and people – including domestic drinking water. There are multiple data sources used to determine water supply.

In normal years, snowpack serves as natural storage that allowed water to gradually melt through spring and summer. This makes water available in rivers and streams for fish, farms and people when most needed. But these patterns are no longer reliable in Washington.

Snowpack supports entire ecosystems and water resources, such as drinking water and agriculture. Measuring the snowpack in the mountains helps us know how much water we'll have for the rest of the year.

In Washington, the legal definition of drought is based on water availability. A drought emergency is declared when water supply conditions are, or are expected to, fall below 75 percent of average, and there is potential for undue hardships due to low water supply. In 2020, the Legislature also authorized Ecology to issue a “drought advisory” when drought conditions are developing, but an emergency declaration is not justified.

Drought emergency declarations enable Ecology to to help mitigate the impacts of drought, lessening the negative effects it can have on water supplies for people, farms, and fish. Drought advisories are a voluntary tool to support water conservation and public readiness. 

Prior to the current legislative framework:

• 1977 – Statewide (Governor convened "Ad Hoc Executive Water Emergency Committee" Feb. 16, 1977 -- pre current drought framework)
• 1988 – Statewide (Very dry 1987 resulted in legislation enacting current drought framework- RCW 43.83B)

Following years were based on current drought framework from 1989 (RCW 43.83B.405 and WAC 173-166-050):

• 1992 – Yakima Basin
• 1994 – Yakima Basin
• 2001 – Statewide
• 2005 – Statewide
• 2006 – Lyre-Hoko
• 2015 – Statewide
• 2019 – 27 Watersheds, including the Yakima, but excluding SE Washington and Puget Sound region
• 2021 – Statewide, except for central Puget Sound (Green, Cedar, Snohomish WRIAs)
• 2022 – Partial extension of 2021 declaration for a few watersheds in eastern WA, with the remainder of eastern Washington being put in Drought Advisory status. (Ecology pulled back the declaration in July after extending it in late May).
• 2023 – 12 watersheds/12 counties in the emergency drought declaration with a statewide advisory.
• 2024 – Statewide declaration, except for the areas served by the utilities of Everett, Seattle, and Tacoma.
• 2025 – 22 watersheds, except for the areas served by the utilities of Everett, Seattle, and Tacoma.