A study of Pequea Creek included measurement of streamflow and collection of water and bottom-material samples during selected base-flow and storm periods from February to December 1977. Samples were analyzed for nitrogen and phosphorus species, suspended sediment, organic carbon, and pesticides. Daily mean constituent concentrations and discharges transported from the basin were computed for a gaging station near the mouth. Intermittent constituent mean concentrations and discharges were computed for storms at the six subbasin sites. The objective of this project was to assess the magnitudes and types of nonpoint discharges that affect the water quality of Pequea Creek. The project included the determination of (1) the total discharges of suspended sediment, nitrogen, and phosphorus from the basin; (2) intermittent storm and base-flow discharges from six subbasin sites of varying size, geology, and land use; (3) the difference in magnitudes of the discharges during base-flow periods and storms; and (4) which variables most affect the transport of these constituents. The yields measured from the Pequea Creek basin for the period February to December 1977 were among the highest measured in the lower Susquehanna River basin. Some preliminary relations between constituents were examined using linear regression techniques on all of the data for each site. Direct runoff transported the majority of the suspended sediment, total phosphorus, and suspended organic carbon from the basin; the other constituents were transported mainly during base flow. (USGS).
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USGS Numbered Series
Nonpoint-source discharges in Pequea Creek Basin, Pennsylvania, 1977