Columbia river basin groundwater levels are dropping across eastern Washington, and 1 funded program is already pumping less

Columbia river basin groundwater levels dropping across eastern Washington

Columbia river basin groundwater levels dropping is already a documented fact, not a future risk, and a July 2026 draft report from the Washington Department of Ecology and Washington State University confirms it again across eastern Washington. Groundwater is water stored underground in layers of rock, sand and clay called aquifers, pulled to the surface through wells for drinking and irrigation. The Columbia River Basin covers nearly 70% of Washington State, and the state models 4 aquifer layers beneath it, from shallowest to deepest, the Overburden, the Saddle Mountains, the Wanapum and the Grande Ronde. A 2021 forecast already found most of those layers declining, based on real monitoring wells, and the 2026 update reaffirms it.

Federal drought data valid September 1, 2026 puts 71.6% of Washington State in a drought condition, unchanged from the week before, affecting 3.2 million residents. July 2026 ranked as the 30th driest July in Washington since 1895, and the first 7 months of the year rank as the 27th driest such stretch on record.

We are already experiencing the increased pressures that come from consecutive droughts.

Melissa Downes, projects section manager for the Washington Department of Ecology Office of Columbia River, quoted by Columbia Insight. Source 2.

A model with 4 scenarios, and 1 lever that could reverse decline

The 2026 forecast tests 4 future scenarios for the aquifer through 2050, comparing an average of current conditions, 2015 to 2022, against an average of future conditions, 2045 to 2050. Without a change in pumping or recharge, water added back into an aquifer by rain, snowmelt or rivers seeping down, the report states groundwater levels will continue to decline across much of eastern Washington and in all 4 aquifer layers. The deepest layer, the Grande Ronde, shows the most spatially extensive and steepest declines of the 4.

1 scenario could reverse rather than only slow the decline. A 15% increase in recharge appears large enough to alter the direction of groundwater change in the 2 shallower layers, even with pumping also rising, the report states. The 2 deeper layers receive negligible natural recharge in the middle of the aquifer system, so their future rests on pumping choices, not rainfall. Reading the full 86 page report surfaces a caution not found in any summary of it. The report states its own recharge estimates are likely overestimated across the aquifer, especially in the deeper layers, and that the model represents flow at a regional scale only, not a scale precise enough to predict an exact water level at 1 location.

We studied this topic because conservation alone will not solve all water supply challenges in the Columbia Basin.

Emily Tasaka, communications manager for the Washington Department of Ecology Office of Columbia River, quoted by Columbia Insight. Source 2.

What is being done about declining groundwater in Washington State

1 program is already cutting pumping in the worst affected area, the Odessa Subarea. The Odessa Groundwater Replacement Program is converting 87,600 acres of irrigated land from groundwater to river water within the footprint of the original Columbia Basin Project, according to the state forecast. The state forecast finds the program has the potential to offset as much as 30 years of decline in the Grande Ronde layer, and to a lesser extent in the Wanapum layer. Washington State has invested more than 126 million dollars in the program since 2004, the Bureau of Reclamation has added more than 45 million dollars, and landowners raised 16.8 million dollars more through municipal bonds, for a combined total of more than 187.8 million dollars, a MAOWCE calculation adding the 3 figures the East Columbia Basin Irrigation District states separately. That funding converts about 19% of the district total 472,000 acre service area, another MAOWCE calculation, a reminder that most of the district still pumps groundwater outside the program.