Evaluation of water resources in the Reedsport area, Oregon

Abstract

The water supply for the Reedsport area is obtained from Clear Lake, a 310-acre coastal lake that contains 16, 600 acre-feet of water at full-pool. The lake receives about 6,000 acre-feet of water annually from runoff and direct precipitation, and it loses about 600 acre-feet by evaporation. The 2,100 acre-feet diverted annually for public supply is about two-thirds of the ' usable storage capacity ' of the lake volume above the water-supply outlet pipe. Clear Lake is classified as a warm monomictic lake; that is, it is thermally stratified except during winter. The water of Clear Lake is of the sodium chloride type and is low in dissolved solids and nutrients. The water is considered to be of good quality for public supply, on the basis of biological and chemical constituents analyzed, which include trace elements pesticides, and organic material. The only ground-water source with potential to supply the needs of the Reedsport area is the dune sand-marine aquifer between U.S. Highway 101 and the coast. That aquifer consists largely of medium- to fine-grained sand with a variable saturated thickness of at least 90 feet. The aquifer is estimated to contain at least 12 billion gallons of water and to receive annual recharge from precipitation equivalent to 10 million gallons per day. Wells in the most productive part of the aquifer could be expected to yield a few hundred gallons per minute. The only identified water-quality problem is excessive iron reported in water from some wells. Either Clear Lake or the major aquifer could supply the Reedsport area 's aticipated year 2000 need of about 2.4 million gallons per day.