The geohydrology of infiltration from five tributary streams along a 3.6-mile reach of Marsh Creek valley in north-central Pennsylvania was investigated during 1983-85. Marsh Creek valley is underlain by up to 100 feet of stratified drift that overlies Devonian bedrock. The stratified drift is overlain by up to 30 feet of alluvial-fan deposits near the tributary streams.
Four of the five tributary streams lose large amounts of water to the stratified-drift aquifer in Marsh Creek valley. Along reaches away from the valley wall, infiltration losses from the streams averaged about 2 cubic feet per second per 1,000 feet of wetted channel length. Estimated hydraulic conductivity of the deposits near these streams ranges from 31 to 100 feet per day and averages 61 feet per day. Silty beds of lower permeability near the streams may significantly affect infiltration. The low permeability of the sediments near the fifth stream, which probably consist largely of fine-grained alluvium and swamp deposits, may account for the lack of infiltration losses along this stream.
Tributary-stream infiltration accounted for more than 70 percent of the estimated recharge to the stratified-drift aquifer along the reach investigated during water year 1985, in which annual precipitation was below average. The sources of recharge and their estimated rates were: (1) direct infiltration of precipitation on the valley, 1.7 cubic feet per second; (2) unchanneled runoff and ground-water inflow from the uplands, 2.7 cubic feet per second; and (3) tributary-stream infiltration from Asaph Run, 3.7 cubic feet per second, Straight Run, 3.7 cubic feet per second, Dantz Run, 1.2 cubic feet per second, and Canada Run, 1.9 cubic feet per second. The temporal variation in recharge from tributary-stream infiltration greatly affects drawdowns caused by pumping from the wellfield at the National Fisheries Research and Development Laboratory near Straight Run.