Columbia Basin Groundwater Management Area (GWMA) Groundwater Resources

Evidence has been mounting for several years that groundwater resources in Adams, Franklin, Lincoln and Grant Counties of Washington State are declining – in some cases at an alarming rate. These resources are used for agricultural, industrial and municipal purposes and as such are a vital element of the region’s economy.

The Columbia Basin Ground Water Management Area (GWMA) is a grass-roots effort to further understanding of the presence, availability and utilization of groundwater resources throughout the four counties which together cover over 8,300 square miles.

This understanding is already improving resource management and is positioned to support future water resource planning, including the pursuit of water supply options.

Underpinning this effort is the development of a hydrogeologic framework for the Columbia River Basalt Group (CRBG) and interstitial/overlying sediments, and construction of a groundwater flow model encompassing the four counties. The CRBG comprises several hundred continental flood basalt flows that collectively reach over 10,000 feet thick and cover about 60,000 square miles in the semi-arid areas of Washington, Oregon, and western Idaho. The CRBG contains vertically discrete aquifers located within basalt interflow zones, separated by low-permeability basalt flow interiors. These aquifers are further compartmentalized laterally by faulting and folding. As the availability of resources declines, drilling to depths exceeding 3,000 feet is increasingly necessary to obtain high-yielding wells.

Translating the developing conceptual model, complete with the natural and man-made complexities described above, is a challenging task that is being undertaken jointly by SSP&A together with GSI Water Solutions in collaboration with the GWMA.