GSI’s team worked with stakeholders to develop shallow aquifer recharge (AR) as a sustainable and innovative water resource tool to restore diminished aquifer levels and stream baseflows which benefits both fish, habitat, and local irrigators.

Background

The Walla Walla Basin (Basin) used to support healthy populations of salmon, steelhead, and bull trout. However, increased demands on water resources from agricultural and urban development have significantly reduced streams and groundwater levels in the Basin, threatening the flora and fauna of the area. In the 1990s, in an effort to avoid a confrontation over water, water resources stakeholders banded together to work cooperatively and improve aquatic habitat and maintain water supplies for both environmental and human uses.

GSI’s Solution

In the early 2000’s GSI’s team started working with the Walla Walla Basin Watershed Council (WWBWC), the Walla Walla Watershed Alliance, Walla Walla County, and Gardena Farms Irrigation District #13 to develop aquifer recharge (AR) as a tool to restore the diminished aquifer levels and stream baseflows. Using our knowledge of Walla Walla Basin hydrogeology and our experience in aquifer storage and recovery (ASR) and AR, we assisted these stakeholders with a variety of projects, all focused on AR and stream flow enhancement.

In order to inform the design and implementation of several AR projects, we started by defining the hydrogeologic framework of the aquifer system across the basin in a geographic information system (GIS) format. The GIS formatted tool allowed the WWBWC to further evaluate and model specific aquifer issues in the future. An assessment of the aquifer and groundwater availability was then conducted, followed by implementation of AR projects and an expanding WWBWC’s groundwater flow modeling efforts. Recent AR project work has included testing the feasibility of using winter/spring surface water runoff in several areas. Results were promising and ultimately, local stakeholders will eventually be able to use AR as a tool for addressing the area’s water challenges in a collaborative and environmentally-friendly manner.