June to September 2025 Edition
Mid-Summer Hydrologic Conditions Update By Tom Ring – retired Hydrogeologist with the Yakama Nation Water Resources Program I. Executive Summary Washington State is experiencing severe drought conditions across most regions in 2025, with water supply declining significantly throughout the summer. The drought area has expanded from the Yakima Basin to include most of the Cascades, north central Washington, and portions of the Olympic Peninsula due to rapid snowmelt and exceptionally low precipitation. All watersheds are forecast to have below-average runoff, with most areas experiencing water supply in the bottom 20th percentile and streamflow forecasts for April through September falling into low single-digit percentiles. The impacts are most severe in the Yakima Basin, Washington's agricultural heartland, where irrigation districts are receiving only 40% of normal water supply through prorationing. Following three consecutive drought years, reservoir storage reached record low levels in August—the lowest in the period of record. This has forced major irrigation districts to implement emergency measures, with some shutting off water supplies as early as mid-August. The Kittitas Reclamation District exhausted its allocation on August 13, while Roza Irrigation District expects to end deliveries by September 19. Beyond agriculture, environmental systems are under extreme stress. Fish-bearing streams are dewatering mid-summer, prompting emergency measures such as canal water releases to maintain minimum flows. Despite reduced target requirements, instream flows for salmon remain at critically low levels, threatening ecosystem health and fish survival. Looking ahead, the outlook remains concerning. Carryover storage heading into 2026 will be extremely low, requiring exceptional winter precipitation to prevent continued prorationing next irrigation season. The current three-year drought represents the most severe water supply crisis since the 1992-1994 drought period, with some water managers reporting the worst conditions of their careers. Water supply has continued to decline in Washington State over the summer. Between April and June, rapid snowmelt and low precipitation caused the area covered by drought declarations to expand from just the Yakima basin to include most of the Cascades, north central Washington, and a portion of the Olympic Peninsula. Precipitation for the year remains well below average, and streamflow forecasts for April to September are well below average, with many low single digit percentiles. In the Yakima basin, where irrigated agriculture is heavily dependent on reservoir releases, storage volumes reached record low levels in early August due to a combination of low runoff and low carryover (year to year) storage following last year’s drought. This brief update includes information from state and federal agencies. II. Statewide View In late July, Caroline Mellor gave a drought update to an AWRA lunch meeting1. The presentation covered the state drought declaration process, gave an update on water supply conditions, and discussed next steps for managing the ongoing drought. Ms. Mellor will be speaking on drought at the AWRA State Conference on October 14th in Seattle. On June 5, 2025, Ecology issued a drought emergency declaration in the North and Central Cascade Mountains, parts of north central Washington, and parts of the Puget Sound area, due to low snowpack, early and rapid snowmelt and a dry April and May.
State law defines two criteria for drought.
Both criteria have different local implications depending on human and ecosystem concerns and infrastructure. As in 2024, the major Puget Sound population centers are not included in the 2025 drought declaration due to having sufficient storage capacity to get through summer 2025. By contrast, reservoir storage in the Yakima Project reservoirs at the beginning of the irrigation season (carryover storage) was extremely low and meager snowpack offered no realistic hope of recovering to full water supply.
All watersheds in Washington are forecast to have below average runoff, including those not included in the drought declaration.3
Projected water supply is below the 20th percentile in most of Washington.4 Snowpack has melted off, and there is little likelihood of precipitation events causing large improvements in water supply at this point in the water year. III. Yakima Basin Water supply for irrigated agriculture, the largest water user in the Yakima Basin, was developed to take advantage of copious spring and early summer snowmelt runoff augmented by reservoir storage that amounts to about one third of mean annual runoff. With the development of Yakima Project storage by the Bureau of Reclamation beginning in 1905, preexisting irrigators diverting from the Yakima River were essentially guaranteed a full water supply, while newly created irrigation districts would receive a pro-rata share of remaining total water supply. Prorationing stands at 40% as of August 19th and is projected to stay at that level through the end of September. Proratable supply has been revised downward through the irrigation season as hot dry conditions persisted. The proration index is used to calculate the “bucket” for proratable districts. They can use their bucket at a rate that best suits the demand determined by their cropping patterns. For example, Kittitas Reclamation District (KRD) and Roza Irrigation District are both 100% proratable. As such they each receive the same percentage their annual allotment, but due to fundamental differences in crop types the two districts choose to receive their water on quite different schedules. Both Urban Eberhard, KRD manager and Scott Revell, Roza ID manager have stated that this is the worst year during their careers, although these two districts manage short water supply years in two different ways. Farmers on KRD mostly grow Timothy Hay and maximize irrigation until the water runs out. The early shutoff means hay growers will not get the revenue from later season hay cuttings. The hay will go dormant and return the following year, although reportedly with less vigor after the prolonged lack of water. Following this pattern, KRD exhausted its bucket and shut off for the season on August 13th. Some KRD users on higher ground have orchards and rely on wells after the ditch water ceases. Roza, by contrast, is heavily planted in orchard and vineyard crops. The trees need water later in the season both to support development of fruit and to keep the trees alive. In drought years, Roza cuts diversions in early season to conserve their bucket for late season. In 2025, Roza expects to end deliveries on September 19th. At this point in the irrigation season, runoff from snowmelt is minimal, and Reclamation is essentially rationing storage to the proratable irrigation districts while maintaining target flows below Sunnyside Dam as mandated by federal law. Instream target fish flows are reduced in seasons of low total water supply available. Groundwater driven baseflows from unregulated tributaries contribute relatively small flows in comparison with reservoir releases. Urban Eberhard, manager of the proratable Kittitas Reclamation District who has been working on Yakima Basin water issues since High School, is seeing lower flows than he has previously seen in Manastash Creek, a Yakima tributary in the Kittitas Valley. He attributes this to three consecutive drought years drying up the “sponge” that usually continues to contribute baseflows after snowmelt ceases, an opinion supported by soil moisture data on drought.gov showing soil moisture well below average in the Washington Cascades. Seeing the problem with fish-bearing Kittitas County tributaries dewatering mid-summer in 2015, Eberhard began releasing water from the KRD canal into several tributaries including Manastash. The district has continued this operation each year since even after their irrigation supply has been exhausted, operating the canal solely to maintain flow in fish stream. In 2015 Eberhard received the AWRA-WA award for outstanding contributions to water resources in recognition of this program.
In August, storage in the Yakima Project reservoir system declined to the lowest volume in the period of record. This plot shows the effects of the current 3-year drought. The previous “low water mark” and previous 3-year drought was 1992-1994. (source USBR August update)
Summary from Reclamation August Update Record low storage, 40% for proratables Low July precipitation (for water year, 76.9%) Low flows for salmon Carryover storage will be extremely low. A very good winter will be needed to prevent prorationing in the 2026 irrigation season. IV. Ongoing Processes The website for the Water Resources Advisory Committee describes some of the tools available to Ecology during declared droughts including expedited water transfers, grants to mitigate hardships, and others. Infrastructure improvements, conservation measures, and habitat improvements for fisheries are included. Typically in the Yakima basin, many water transfers are processed during droughts. After the 1994 drought, basin stakeholders developed protocols for acceptable water transfers in accordance with a clause in the 1994 Yakima River Basin Enhancement Project act. A Water Transfer Working Group has been in place since the 2001 drought to vet transfers according to criteria agreed to by major water users and agencies. In the Dungeness, the Washington Water Trust is working with irrigators on a program to temporarily reduce diversions in a coordinated way to allow pulse flows for fish. In summary, 2025 is a substantial drought across much of the state. Precipitation is well below average. Streamflows are in the very low range. In the Yakima basin, which is dependent on both spring/summer snowmelt runoff and reservoir storage, both are quite low and proratables irrigators, about half the irrigation in the basin are receiving 40% of full supply and instream flows for fish are in the low range. 1 You can find the link to the event recording, here: https://www.waawra.org/event-6257671. |
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