T81 Assessing Groundwater Availability and Sustainability I

Monday, 1 November 2010
8:00 AM - 12:00 PM
Room 612

GROUNDWATER AVAILABILITY OF THE COLUMBIA PLATEAU REGIONAL AQUIFER SYSTEM, WASHINGTON, OREGON, AND IDAHO

Paper number: T81-3
Program: Technical Sessions
Time: 8:25 AM – 8:40 AM

Authors

Abstract

The Columbia Plateau Regional Aquifer System covers more than 44,000 square miles of eastern Washington and Oregon 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 widespread water-level declines caused by pumping, corresponding reductions in base flow to rivers and associated effects on water temperature and quality, and effects of climate change on groundwater recharge, base flow, and groundwater availability.

The U.S. Geological Survey (USGS) Groundwater Resources Program is assessing the availability and use of the Nation’s groundwater resources and developing tools to help evaluate future system response to various human and environmental demands and climate change. As part of the National assessment program, USGS Water Science Centers in Washington, Oregon, and Idaho initiated a study of groundwater availability of the Columbia Plateau Regional Aquifer System in 2008. The major study elements include documenting changes in the status of the system, quantifying the hydrologic budget, updating the regional hydrogeologic framework, and simulating the system with a numerical groundwater flow model.

Region-wide synoptic water-level measurements were made in spring 2009 to help assess changes in the status of the system. MODIS (Moderate Resolution Imaging Spectroradiometer) and other satellite imagery were used to help estimate irrigation water use on a regional scale from 1989-2007. Public supply and domestic water use was estimated using public water supply system information, census data, and per capita water-use rates. The regional hydrogeologic framework was updated by incorporating new information from large-scale hydrogeologic studies and using geostatistical techniques. Work is ongoing to complete development of the conceptual model, including a first-order hydrologic budget, and construction of a groundwater flow model.