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The U.S. Geological Survey, in cooperation with the Susquehanna River Basin Commission and the Pennsylvania Department of Environmental Resources, conducted a study as part of the U.S. Environmental Protection Agency's Chesapeake Bay Program to determine the effects of nutrient management on surface-water quality by reducing animal units in a 0.43 square-mile agricultural watershed in York County. The study was conducted primarily from October 1985 through September 1990 prior to and during the implementation of nutrientmanagement practices designed to reduce nutrient and sediment discharges. Intermittent sampling continued until August 1991. The Bald Eagle Creek Basin is underlain by schist and quartzite. About 87 percent of the watershed is cropland and pasture. Nearly 33 percent of the cropland was planted in corn prior to nutrient management, whereas 22 percent of the cropland was planted in corn during the nutrient-management phase. The animal population was reduced by 49 percent during nutrient management. Average annual applications of nitrogen and phosphorus from manure to cropland were reduced by 3,940 pounds (39 percent) and 910 pounds (46 percent), respectively, during nutrient management. A total of 94,560 pounds of nitrogen (538 pounds per acre) and 26,400 pounds of phosphorus (150 pounds per acre) were applied to the cropland as commercial fertilizer and manure during the 5-year study. Core samples from the top 4 feet of soil were collected prior to and during nutrient management and analyzed for concentrations of nitrogen and phosphorus. The average amount of nitrate nitrogen in the soil ranged from 36 to 135 pounds per acre, and soluble phosphorus ranged from 0.39 to 2.5 pounds per acre, prior to nutrient management. During nutrient management, nitrate nitrogen in the soil ranged from 21 to 291 pounds per acre and soluble phosphorus ranged from 0.73 to 1.7 pounds per acre. Precipitation was about 18 percent below normal and streamflow was about 35 percent below normal prior to nutrient management, whereas precipitation was 4 percent above normal and streamflow was 3 percent below normal during the first 2 years of nutrient management. Eightyfour percent of the 20.44 inches of streamflow was base flow prior to nutrient management and 54 percent of the 31.14 inches of streamflow was base flow during the first 2 years of the nutrient-management phase. About 31 percent of the measured precipitation during the first 4 years of the study was discharged as surface water; the remaining 69 percent was removed as evapotranspiration or remained in ground-water storage. Median concentrations of total nitrogen and dissolved nitrate plus nitrite in base flow increased from 4.9 and 4.1 milligrams per liter as nitrogen, respectively, prior to nutrient management to 5.8 and 5.0 milligrams per liter, respectively, during nutrient management. Median concentrations of ammonia nitrogen and organic nitrogen did not change significantly in base flow. Median concentrations of total and dissolved phosphorus in base flow did not change significantly and were 0.05 and 0.03 milligrams per liter as phosphorus, respectively, prior to the management phase, and 0.05 and 0.04 milligrams per liter, respectively, during the management phase. Water-Resources Investigations Report 93-4069 Concentrations and loads of dissolved nitrite plus nitrate in base flow increased following wet periods after crops were harvested and manure was applied. During the growing season, concentrations and loads decreased as nutrient utilization and evapotranspiration by corn increased. About 4,550 pounds of suspended sediment, 5,300 pounds of nitrogen, and 70.4 pounds of phosphorus discharged in base flow in the 2 years prior to nutrient management. During the first 2 years of nutrient management about 2,860 pounds of suspended sediment, 5,700 pounds of nitrogen, and 46.6 pounds of phosphorus discharged in base flow. Prior to nutrient management, about 260,000 pounds of suspended sediment, about 2,180 pounds of nitrogen, and about 235 pounds of phosphorus discharged in stormflow. During the first 2 years of nutrient management about 464,000 pounds of suspended sediment, 6,120 pounds of nitrogen, and 912 pounds of phosphorus discharged in stormflow. The seasonal rank-sum test indicated that significant differences were detected in the medians of total nitrogen and dissolved nitrite plus nitrate in base flow prior to and during nutrient management. The seasonal Kendall test indicated significant upward trends in concentrations and loads of total nitrogen and dissolved-nitrite plus nitrate measured in base flow during the entire study. Neither significant differences nor trends were detected in the concentrations and loads for ammonia, ammonia plus organic nitrogen, phosphorus, or suspended sediment in base flow. Water-Resources Investigations Report 93-4069 INTRODUCTION The U.S. Geological Survey (USGS), in cooperation with the Susquehanna River Basin Commission (SRBC) and the Pennsylvania Department of Environmental Resources (PaDER) Bureau of Land and Water Conservation, conducted a study to determine the effects of agricultural best-management practices on surface-water quality in the Bald Eagle Creek watershed (site 1, fig. 1) from October 1, 1985, to September 30, 1990. The site is underlain by noncarbonate rock and is one of three small agricultural watersheds in the Lower Susquehanna River Basin that were studied prior to and during the implementation of nutrient management at the watersheds. This report includes a comparison of land-use and water-quality data from Bald Eagle Creek with data from Brush Run (site 2, fig. 1, also underlain by noncarbonate rock) and the Nutrient-Management Subbasin located in a carbonate-rock area (site 3, fig. 1) that is part of the Conestoga River headwaters being studied by Fishel and others (1992) as part of the Rural Clean Water Program (RCWP). The full history of this study's conception is described in the characterization report (Fishel and others, 1991). In 1982, the RCWP initiated a 10-year study of the Conestoga River headwaters to determine the effects of agriculturalmanagement practices on surface-water and ground-water quality. One of three components of the Conestoga River Headwaters Project was to evaluate the effects of nutrient management in a small intensively farmed watershed, the Little Conestoga Creek watershed, underlain by carbonate rock. Inasmuch as there was a need for a corresponding program in areas underlain by noncarbonate rocks in the Lower Susquehanna River basin, this study and a study of the Brush Run watershed were initiated by the USGS in 1985 (Fishel and others, 1992). The study was part of the U.S. Environmental Protection Agency (USEPA) Chesapeake Bay Program. The results from this study were planned to be compared to results from the carbonate-rock areas being studied for the RCWP, such as the NutrientManagement Subbasin in the Little Conestoga Creek headwaters, and to results from Brush Run Creek, a second site in noncarbonate rock. Initially, agricultural-management plans were to be designed and implemented at two of the farms in the 0.43-mi2 Bald Eagle Creek study area and were to consist of a combination of management practices. Management plans included recommendations to install terraces, diversions, sediment-detention ponds, animal-waste storage facilities, barn gutters, and other innovative techniques to control nutrient and sediment loads in surface runoff. The installation of the management practices were to reduce the amount of nutrients available for leaching to the ground water and also discharged in base flow or storm runoff. Nutrient applications were to be balanced with crop requirements to obtain maximum crop yields. However, in September 1987, one of the cooperating fanners was permitted to withdraw from his Chesapeake Bay Program cost-sharing management plan after developing a medical difficulty. He later sold his dairy herd and changed his cropping patterns from predominantly corn to alfalfa. Subsequently, a second farmer within the study area sold his farm. The new owner reduced the number of animal units by reducing the dairy population at the farm. Monitoring continued at the site to determine the effects that these management changes-a reduction of animal units, manure applications, and corn production-would have on surface-water quality in the Bald Eagle Creek Basin. Because a management practice was not implemented to control storm-water runoff, the monitoring effort was reduced and the project scope changed. The continuous streamflow gage and precipitation gage were discontinued in September 1989. After September 1989, the project scope concentrated on base-flow quality; however, in order to fully understand the hydrologic conditions at the site additional data from the ground-water system needed to be collected. Attempts were then made to collect limited ground-water information so that changes observed in water quality could be correlated with land-use activities that could potentially effect the base flow. Even though the ground-water basin was somewhat different than the surface-water basin, the assumption was made that any changes in the water quality of base flow were caused by land-use changes within the surface-water basin. Measurement of intermittent base-flow quantity and quality continued until August 1991 in an attempt to detect changes in water quality from the reduction in applications of animal waste. Water-Resources Investigations Report 93-4069 Purpose and Scope This report provides an evaluation of the effects of agricultural-management practices, with emphasis on the effects of reductions of (1) animal units, (2) nutrient applications, and (3) com production on the surface-water quality of a 0.43-mi2 watershed (fig. 2) in the Bald Eagle Creek headwaters near Fawn Grove, in York County, Pa. Data collected from the premanagement pha

water-resources investigations report

Hydrology and the effects of selected agricultural best-management practices in the Bald Eagle Creek watershed, York County, Pennsylvania, prior to and during nutrient management: Water-quality study for the Chesapeake Bay Program