Groundwater

The Columbia River Basalt Group (CRBG) consists of a thick sequence of Miocene flood basalt that covered northern Oregon, eastern Washington, and western Idaho between 17 and 6 million years ago. It is an important regional aquifer system, and, in its folded and faulted flows, it records the late Cenozoic structural evolution of much of the Pacific Northwest.

The Columbia Plateau Regional Aquifer System (CPRAS) covers about 44,000 square miles of eastern Oregon and Washington and western Idaho. The primary aquifers are basalts of the Columbia River Basalt Group and overlying basin-fill sediments. Groundwater availability issues in the basin include: 1) widespread water-level declines caused by pumping, 2) reduction in base flow to rivers and associated...

The U.S. Geological Survey (USGS) studies the water resources of the Willamette River Basin. Here you will find a description of the study, as well as information and data resulting from this work.