A reconnaissance of the water resources of the Shoalwater Bay Indian Reservation and adjacent areas, Pacific County, Washington, 1978-1979

A 1978-79 reconnaissance of the quantity and quality of water in the Shoalwater Bay Indian Reservation yielded information needed by the Shoalwater Bay Indian Tribe to plan future use of these resources. Ground water from the local artesian aquifer is suitable for most uses and it is estimated that yield can be as much as 100 to 500 gallons per minute. Long-term yields cannot be calculated from available data. Data from 1968-80 show no measurable declines in water levels or rates of flow due to pumping from the aquifer. Analysis of ground-water samples indicated no seawater intrusion into the aquifer. Mean monthly flows of two streams in the study area ranged from 0.53 to 3.28 cubic feet per second in February 1979. Estimated average 7-day low flows with a recurrance interval of 2 years ranged from 0.3 to 3.0 cubic feet per second. Analyses of surface-water samples indicated concentrations of Aldrin, DDD, DDT, Dieldrin, Diazinon , and Ethyl Parathion that exceeded EPA limits for protection of marine life. Samples of the stream-bottom material in one stream had high concentrations of Aldrin, DDD, DDE, DDT, Dichlobenil, and Dieldrin. Tribally owned tidelands into which these streams flow may be contaminated by these toxic chemicals. (USGS)