A Complex Basin
The Walla Walla watershed basin is unique as its rivers and streams flow through both Oregon and Washington states and are bordered by the Columbia and Snake rivers. Since time immemorial, the confluence of the Columbia with the Walla Walla, Snake, and Yakima rivers has been home to the Confederated Tribes of the Umatilla Indian Reservation. Today, the basin encompasses 1,758 square miles of land and has three subbasins: the Touchet River subbasin, the Walla Walla subbasin, and the Mill Creek subbasin. As both the rural and urban communities continue to develop in the subbasins, water must be efficiently managed for the benefit of communities and wildlife.
An Overallocated Basin
The Walla Walla watershed basin, like many others in the region, has been overallocated for hundreds of years — meaning there are more legal rights to use water than there is water available for use.
The Walla Walla River, the largest river in the basin, has been seasonally running dry since the development of irrigated agriculture in the early 20th century. This prevented spring Chinook salmon and steelhead from migrating, or moving up and down the river, for spawning. Today, spring Chinook have been extirpated from the basin, and steelhead are critically imperiled. Not only are this lack of stream flows a barrier to fish, but the low river water levels also limit communities’ ability to use their water rights for irrigating farmlands. Creating innovative solutions to ensure water is consistently present in quantities for use by farms and fish has been a challenge for the basin.
A Changing Basin
The Walla Walla watershed basin receives little rain in summer, making snowpack and snowmelt critical to maintaining water supply. Yet, a changing climate is impacting the timing and quantity of water in the basin. Studies indicate the basin’s snow melt is happening earlier than in past decades, and maybe experiencing one of the largest declines in snowpack in the Pacific Northwest. The Walla Walla River is expected to decrease by up to 66 percent by the 2040s and as much as 89 percent by the 2080s.
Wildfires and floods are also increasing in frequency because of climate change. These events change the landscape and affect water availability, leading to more frequent wildfires and increased flooding. These extreme fluctuations create the perfect storm to damage habitat and impede streamflow.
Learn more about the
Walla Walla Basin
Explore the interactive story map and see how the region is addressing these challenges!