By Daniel T. Snyder, David S. Morgan, and Timothy S. McGrath
USGS Water-Resources Investigations Report 92-4010, 34 p., 3 tables, 16 figs., 1 plate.
Available from U.S. Geological Survey, 10615 S.E. Cherry Blossom Drive, Portland OR 97216 (ph: 503-251-3201, e-mail: info-or@usgs.gov) and U.S. Geological Survey, Branch of Information Services, Box 25286, Denver, CO 80225 (303-202-4210).
Abstract
The average recharge rate in the Portland Basin in northwestern Oregon and southwestern Washington is estimated to be about 22.0 inches per year. Of that amount, precipitation accounts for about 20.8 inches per year, runoff into drywells accounts for 0.9 inches per year, and on-site waste disposal accounts for about 0.4 inches per year. In areas of urban development, however, drywells and on-site waste-disposal systems are a substantial source of recharge, contributing about 38 percent and 17 percent of the total, respectively.
The highest recharge rates (about 49 inches per year) generally are found in the Cascade Range; the lowest recharge rates (near zero) are found along and between the Columbia and Willamette Rivers. Higher recharge rates occur locally in discrete areas owing to recharge from runoff into drywells and on-site waste-disposal systems in urbanized parts of the study area. In these urbanized areas, recharge ranges from 0 to 49 inches per year.
To obtain a copy of the full report, free of charge (while supplies last), click here . Please supply the report title and number, your name, and your address. Thank you.
Oregon District Online Publications
Page
Oregon District Home Page