Hydrologic reconnaissance near Fourth of July Creek, Seward, Alaska

The 1.3-square-mile alluvial fan of Fourth of July Creek, Seward , Alaska, is being developed as an industrial area and port. Fourth of July Creek is a glacier-fed stream that occupies a braided channel near the middle of the fan. The presence of glacial flow during the summer and low discharge during the winter make streamflow a poor source of water for municipal and industrial use. Water infiltrates the fan from streams and precipitation and recharges an unconfined alluvial aquifer. Average recharge is 40-50 cubic feet per second, and ground water flows toward the coast where it discharges in springs and a 0.3-mile gaining reach of the creek. Properties and concentrations of all measured chemical constituents of water samples from two wells were less than the maximum amounts recommended for drinking water. Both the aquifer and the overlying unsaturated materials are coarse grained. The coarse-grained materials are poor filters and make the aquifer susceptible to pollution by contaminants disposed of or spilled on the alluvial fan. Avalanches may block the creek and cause flooding by directing streamflow into new or abandoned channels. (USGS)