Water resources near Dillingham in the Bristol Bay Area, Alaska

Dillingham, the largest community in the Bristol Bay area of Alaska, lies near the confluence of the Wood and Nushagak Rivers. Mean annual discharges for the Wood and Nushagak Rivers are 4,824 and 22,650 cu ft/sec. Flows generally are greatest in May through July and lowest in January through April. The surface waters are a calcium bicarbonate type and have low concentrations of dissolved solids and suspended sediments. Water in the Wood-Nushagak estuary near Dillingham during a high tide in autumn 1985 had specific conductance values ranging from 110 to 3,000 microsiemens/cm. Groundwater is the predominant source of public, private, and commercial/industrial supply. Wells range in depth from 20 to 213 ft, yield up to 225 gal/min, and have water levels that range from 4 to 76 ft below land surface. All water levels measured during June and July 1986 were above sea level. Samples of groundwater contained < 500 mg/L dissolved solids but concentrations of iron and manganese were as great as 870 and 1,200 mg/L, respectively. Peak water use is in midsummer. In 1986, peak use in the townsite area was between 300,000 and 400,000 gal/day whereas in previous years it has been as great as 1 million gal/day. (Author 's abstract)