Geology topics

Research about Pennsylvania

Source-linked reports with geographic coverage including Pennsylvania.

At least 361 records · Page 20Linked to original sources

USGS1997

Episodic acidification and changes in fish diversity in Pennsylvania headwater streams

Current water chemistry and fish communities in 70 Pennsylvania streams were compared with historical records to determine whether fish species richness had declined and, if so, the possible role of acidification. First‐, second‐, and third‐order streams were selected, and stream sites sampled during the 1961–1971 survey were resampled during May and June 1994 in the Appalachian Plateaus province and during June 1995 in the Valley and Ridge province. Streamflow was measured and a habitat assessment was completed at each site. Dominant bedrock types influencing the stream sampling site were determined for the Appalachian Plateaus streams. Episodic water chemistry was collected for 39 of the 50 Appalachian Plateaus streams and 14 of the 20 Valley and Ridge streams during the winter and spring of 1996. Thirty‐eight (76%) streams of the Appalachian Plateaus province and 13 (65%) streams in the Valley and Ridge province had a loss of fish species since the 1961–1971 sampling period. Habitat scores were not related to losses of fish species. Of the 53 streams sampled during runoff episodes 22 (42%) increased in total dissolved aluminum by more than 50 μg/L, and 31 (58%) streams decreased in pH by 0.5 units or more. Minnows (Cyprinidae) and darters (Percidae) are sensitive to acidity and were the species most often lost. Streams draining watersheds of the Appalachian Plateaus province dominated by Pottsville bedrock had more acidic water quality during base flow and storm flow sampling periods than streams dominated by Pocono bedrock. The results of this study indicate that many Pennsylvania streams have undergone an alarming reduction in fish diversity during the past 25–34 years. In many of these streams the loss in fish diversity may be attributed to episodic acidification.

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USGS1997

Habitat use and feeding ecology of riverine juvenile American shad

We examined premigratory populations of American shad Alosa sapidissima in the upper Delaware River to determine habitat and microhabitat use, differential prey use among habitat types, and habitat suitability indices for this previously unmodeled life stage. Both seining and diving techniques were used to quantify juveniles in six habitat types with six physical habitat covariables. Plankton and drift samples also were compared with stomach contents within habitats. We found no relation between relative abundance of juveniles and habitat type, which suggests general use of most riverine habitats. Physical habitat variables likewise did not affect use of habitat within ranges recorded, with two exceptions: (1) a positive relationship between abundance and water temperature in riffles and (2) a positive relationship between abundance and percent submerged aquatic vegetation (SAV) cover in SAV habitats. Opportunistic use of prey items was apparent; however, juveniles selected chironomid larvae and pupae and adult terrestrial insects and avoided ephemeropterans. Overlap between diets and available prey was high for most habitat types ( C λ mean = 0.71), especially for riffles ( C λ = 0.91). However, overlap for juveniles foraging at tributary mouths, where they strongly selected adult terrestrial insects, was low ( C λ = 0.49).

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USGS1997

Activities of the United States Geological Survey in Pennsylvania

Since the late 1800's, when the U.S. Geological Survey first established a presence in Pennsylvania, the focus of our work has changed from general hydrologic and geologic appraisals to issue-oriented investigations; from predominantly data collection to a balanced program of data collection, interpretation, and research; and from traditional, hand-drawn mapping to digitally produced coverages with specialized themes. Yet our basic mission has not changed. It is as relevant to the resource issues of today as it was when our geologists first arrived in western Pennsylvania in 1884. Continuing in this proud heritage and tradition, the U.S. Geological Survey is moving confidently toward the next century, evolving organizationally and technologically to better meet the needs of our many constituencies. One major organizational change is the recent accession of employees from the former National Biological Service, who now form the Survey's fourth program division, the Biological Resources Division. These employees join forces with colleagues in our other three divisions: Water Resources, Geologic, and National Mapping. More than any other change in decades, the addition of this biological expertise creates new and exciting opportunities for scientific research and public service. This report provides an overview of recent activities in Pennsylvania conducted by the four program divisions and is intended to inform those interested in U.S. Geological Survey products and services. Additional information is available on our home page (at http://wwwpah2o.er.usgs.gov/). Together with numerous Federal, State, and local agencies and organizations who are our customers and partners, we at the U.S. Geological Survey look forward to providing continued scientific contributions and public service to Pennsylvania and the Nation.

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USGS1997

Water resources data, Pennsylvania, water year 1995. Volume 1: Delaware River basin

Water resources data for the 1995 water year for Pennsylvania consists of records of discharge and water quality of streams; contents and elevations of lakes and reservoirs; and water levels and water quality of ground-water wells. This report, Volume 1, contains (1) discharge records for 76 continuous-record streamflow-gaging stations and 9 partial-record stations; (2) elevation and contents records for 13 lakes and reservoirs; (3) water-quality records for 20 streamflow-gaging stations and 51 ungaged stream sites; and (4) water-level records for 16 network observation wells. Site locations are shown in figures throughout the report. Additional water data collected at various sites not involved in the systematic data-collection program are also presented. These data, together with the data in Volumes 2 and 3, represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, local, and Federal agencies in Pennsylvania.

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USGS1997

Water resources data, Pennsylvania, water year 1996. Volume 1. Delaware River Basin

Water resources data for the 1996 water year for Pennsylvania consists of records of discharge and water quality of streams; contents and elevations of lakes and reservoirs; and water levels and water quality of ground-water wells. This report, Volume 1, contains (1) discharge records for 74 continuous-record streamflow-gaging stations, 7 partial-record stations, and 15 special study and miscellaneous streamflow sites; (2) elevation and contents records for 13 lakes and reservoirs; (3) water-quality records for 20 streamflow-gaging stations and 51 ungaged stream sites; and (4) water-level records for 15 network observation wells. Site locations are shown in figures 6-9. Additional water data collected at various sites not involved in the systematic data-collection program are also presented. These data, together with the data in Volumes 2 and 3, represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, local, and Federal agencies in Pennsylvania.

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USGS1997

Water resources data, Pennsylvania, water year 1996. Volume 2: Susquehanna and Potomac River basins

Water resources data for the 1996 water year for Pennsylvania consist of records of discharge and water quality of streams; contents and elevations of lakes and reservoirs; and water levels and water quality of ground-water wells. This report, Volume 2, contains (1) discharge records for 81 continuous-record streamflow-gaging stations, 16 partial-record stations, and 20 special study and miscellaneous streamflow sites; (2) elevation and contents records for 12 lakes and reservoirs; (3) water-quality records for 7 gaging stations and 46 ungaged stream sites; and (4) water-level records for 30 ground-water network observation wells. Site locations are shown in figures throughout the report. Additional water data collected at various sites not involved in the systematic data-collection program are also presented. These data, together with the data in Volumes 1 and 3, represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, local, and Federal agencies in Pennsylvania.

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USGS1997

Water resources data, Pennsylvania, water year 1996. Volume 3. Ohio River and St. Lawrence River basins

Water resources data for the 1996 water year for Pennsylvania consists of records of discharge and water quality of streams; contents and elevations of lakes and reservoirs; and water levels of ground-water wells. This report, Volume 3, includes records from the Ohio and St. Lawrence River Basins. Specifically, it contains: (1) discharge records for 66 continuous record streamflow-gaging stations and 10 partial-record and miscellaneous streamflow stations; (2) elevation and contents records for 3 lakes and reservoirs; (3) water-quality records for 2 streamflow gaging stations and 18 partial-record stations; and (4) water-level records for 15 network observation wells. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellanious measurements and analyses. These data, together with the data in Volume 1 and 2, represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, Municipal, Local, and Federal agencies in Pennsylvania.

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USGS1997

Water resources data, Pennsylvania, water year 1997. Volume 3. Ohio River and St. Lawrence River basins

Water resources data for the 1997 water year for Pennsylvania consists of records of discharge and water quality of streams; contents and elevations of lakes and reservoirs; and water levels of ground-water wells. This report, Volume 3, includes records from the Ohio and St. Lawrence River Basins. Specifically, it contains: (1) discharge records for 63 continuous record streamflow-gaging stations and 18 partial-record and miscellaneous streamflow stations; (2) elevation and contents records for 11 lakes and reservoirs; (3) water-quality records for 10 streamflow-gaging stations and 18 partial-record stations; and (4) water-level records for 15 network observation wells. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements and analyses. These data, together with the data in Volume 1 and 2, represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, Municipal, Local, and Federal agencies in Pennsylvania.

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USGS1997

Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania: Hydrology of a small carbonate site near Ephrata, Pennsylvania, prior to implementation of nutrient management

The U.S. Geological Survey, in cooperation with the U.S. Department of Agriculture and Pennsylvania Department of Environmental Protection, investigated the effects of agricultural best-management practices on water quality in the Conestoga River headwaters watershed. This report describes environmental factors and the surface-water and ground-water quality of one 47.5-acre field site, Field-Site 2, from October 1984 through September 1986, prior to implementation of nutrient management. The site is partially terraced agricultural cropland underlain by carbonate rock. Twenty-seven acres are terraced, pipe-drained, and are under no-till cultivation. The remaining acreage is under minimum-till cultivation. Corn is the primary crop. The average annual rate of fertilization at the site was 480 pounds per acre of nitrogen and 110 pounds per acre of phosphorus. An unconfined limestone and dolomitic aquifer underlies the site, Depth to bedrock ranges from 5 to 30 feet below land surface. Estimated specific yields range from 0.05 to 0.10, specific capacities of wells range from less than 1 to about 20 gallons per minute per foot of drawdown, and estimates of transmissivities range from 10 to 10,000 square feet per day. Average ground-water recharge was estimated to be about 23 inches per year. The specific capacity and transmissivity data indicate that two aquifer regimes are present at the site. Wells drilled into dolomites in the eastern part of the site have larger specific capacities (averaging 20 gallons per minute per foot of drawdown) relative to specific capacities (averaging less than 1 gallon per minute per foot of drawdown) of wells drilled into limestones in the western part of the site. Median concentrations of soil-soluble nitrate and soluble phosphorus in the top 4 feet of silt- or silty-clay-loam soil ranged from 177 to 329 and 8.5 to 35 pounds per acre, respectively. Measured runoff from the pipe-drained terraces ranged from 10 to 48,000 cubic feet and was 1.7 and 0.8 percent, respectively, of the 1985 and 1986 annual precipitation. An estimated 90,700 cubic feet of surface runoff carried 87 pounds to total nitrogen and 37 pounds of total phosphorus, or less that 0.65 percent of the amount of either nutrient applied during the study period. Rainfall on the snow-covered, frozen ground produced more that half of the runoff and nitrogen and phosphorus loads measured in pipe-drained runoff. Graphical and regression analyses of surface runoff suggest that (1) mean-storm concentrations of total nitrogen species and total phosphorus decreased with increasing time between a runoff event and the last previous nutrient application, and (2) mean total-phosphorus concentrations approached a baseline value (estimated at 2 to 5 milligrams per liter for total-phosphorus concentrations) after several months without nutrient applications. Dissolved nitrate concentrations in ground water in wells unaffected by an on-site ammonia spill ranged from 7.4 to 100 milligrams per liter. Average annual additions and removals of nitrogen were estimated. Nitrogen was added to the site by applications of manure and commercial fertilizer nitrogen, as well as by precipitation and ground water entering across the western site boundary. These sources of nitrogen accounted for 95, 3, 1, and 1 percent, respectively, of estimated additions. Nitrogen was removed from the site in harvested crops, by ground-water discharge, by volatilization, and in surface runoff, which accounted for 42, 28, 29, and less than 1 percent, respectively, of estimated removals.

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USGS1997

Hydrogeology and water quality of the West Valley Creek Basin, Chester County, Pennsylvania

The West Valley Creek Basin drains 20.9 square miles in the Piedmont Physiographic Province of southeastern Pennsylvania and is partly underlain by carbonate rocks that are highly productive aquifers. The basin is undergoing rapid urbanization that includes changes in land use and increases in demand for public water supply and wastewater disposal. Ground water is the sole source of supply in the basin. West Valley Creek flows southwest in a 1.5-mile-wide valley that is underlain by folded and faulted carbonate rocks and trends east-northeast, parallel to regional geologic structures. The valley is flanked by hills underlain by quartzite and gneiss to the north and by phyllite and schist to the south. Surface water and ground water flow from the hills toward the center of the valley. Ground water in the valley flows west-southwest parallel to the course of the stream. Seepage investigations identified losing reaches in the headwaters area where streams are underlain by carbonate rocks and gaining reaches downstream. Tributaries contribute about 75 percent of streamflow. The ground-water and surface-water divides do not coincide in the carbonate valley. The ground-water divide is about 0.5 miles west of the surface-water divide at the eastern edge of the carbonate valley. Underflow to the east is about 1.1 inches per year. Quarry dewatering operations at the western edge of the valley may act partly as an artificial basin boundary, preventing underflow to the west. Water budgets for 1990, a year of normal precipitation (45.8 inches), and 1991, a year of sub-normal precipitation (41.5 inches), were calculated. Streamflow was 14.61 inches in 1990 and 12.08 inches in 1991. Evapotranspiration was estimated to range from 50 to 60 percent of precipitation. Base flow was about 62 percent of streamflow in both years. Exportation by sewer systems was about 3 inches from the basin and, at times, equaled base flow during the dry autumn of 1991. Recharge was estimated to be 18.5 inches in 1990 and 13.7 inches in 1991. Ground-water quality in the basin reflects differences in lithology and has been affected by human activities. Ground water in the carbonate rocks is naturally hard, has a near neutral pH, and contains more dissolved solids and less dissolved iron, manganese, and radon-222 than ground water in the noncarbonate rocks, which is soft, with moderately acidic to acidic pH. Regional contamination by chloride and nitrate and local contamination by organic compounds and metals was detected. Natural background concentrations are estimated to be about 1 milligram per liter for nitrate as nitrogen and less than 3 milligrams per liter for chloride. Ground water in unsewered areas and agricultural areas of the basin has median concentrations of nitrate that are greater than those in ground water from other areas; septic system effluent and fertilizer are probable sources of elevated nitrate. Water samples from wells in urbanized areas contain greater concentrations of chloride than samples from wells in residential areas; road salt is the probable source of elevated chloride. Organic solvents, especially trichloroethylene, were detected in 30 percent of the wells sampled in the urbanized carbonate valley. Most of the organic solvents and some of the metals in ground water were detected near old industrial sites. Base-flow stream quality of West Valley Creek was determined at 15 sites from monthly sampling for 1 year. Differences in stream quality reflect differences in lithology, land use, and point sources in tributary subbasins and mainstem reaches. The chemical composition of base flow in the mainstem is dominated by ground-water discharge from carbonate rocks. Elevated concentrations of nitrate (greater than 3 milligrams per liter as nitrogen) in base flow were measured in a tributary draining agricultural land and in a tributary draining an unsewered residential area. Elevated concentrations of phosphate (greater than 0.5 milligrams per liter as phosphorus) were measured in a stream that receives treated sewage effluent. Discharge of water containing elevated sulfate (about 250 milligrams per liter) from quarry dewatering operations contributes to die increase in sulfate concentration (of 10 to 40 milligrams per liter) in base flow downstream from the quarry. The chloride load at all stream sites is greater than the load contributed by precipitation and mineral weathering to the basin, indicating anthropogenic sources of chloride throughout the basin. The diversity index of the benthic invertebrate community has increased since 1973 at the longterm biological monitoring site on West Valley Creek, indicating an improvement in stream quality. The improvement probably is related to controls on discharges and banning of pesticides, such as DOT, in the 1970's. Concentrations of dissolved constituents, except for chloride, determined for base flow in the autumn do not appear to have changed since 1971. Application of the seasonal Kendall test for trend indicates that concentrations of chloride in base flow have increased since 1971; this increase may be related to the increase in urbanization in the basin. The benthic community structure at the West Valley Creek site in 1991 indicates slight nutrient enrichment. Lithium was detected in ground water and surface water downgradient from two lithiumprocessing facilities. Until 1991, lithium was discharged into a losing reach of West Valley Creek, thus introducing lithium into the ground-water system. The potential for cross-contamination between the ground-water and surface-water systems is great, as demonstrated by the detection of lithium in ground water and surface water downstream and downgradient from the two lithium-processing facilities. The lithium that was discharged into the creek acts as a conservative tracer in gaining reaches of West Valley Creek, maintaining a mass balance and characteristic isotopic signature. Lithium-7/lithium-6 ratios were greater in streams that are affected by sewage and by lithium-processing discharges and in ground water downgradient from the lithium-processing facilities than natural background lithium isotopic ratios.

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USGS1997

Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania: Effects of pipe-outlet terracing on quantity and quality of surface runoff and ground water in a small carbonate-rock basin near Churchtown, Pennsylvania, 1983-89

Terracing effects on surface-runoff and ground- water quantity and quality were investigated by the U.S. Geological Survey, in cooperation with Pennsylvania Department of Environmental Resources, during 1983-89 at a 23.1-acre agricultural site in Lancaster County, Pa., as part of the 1982 Rural Clean Water Program. The site, underlain by carbonate rock, was primarily corn and alfalfa fields; the median slope was 6 percent.Normal precipitation is about 42 inches per year. Average annual runoff was 11 percent and ground- water recharge was 37 percent of precipitation.Runoff quantity, suspended-sediment, and nutrient data, ground-water level and nutrient data, and precipitation-quantity data were collected for 21 months prior to, and 58 months after, pipe-outlet terrace construction. Data were analyzed by use of graphical, regression, covariate, cluster, Mann- Whitney Rank Sum test, and double-mass curvetechniques. Terracing changed runoff characteristics. Storm characteristics were similar throughout the study period. However, after terracing, storms producing less than 0.4 inch of precipitation rarely produced runoff. Total-storm discharge as a function of precipitation did not change significantly throughout the range of runoff-producing storms after terracing. Multiple-discharge peaks on hydrographs before terracing did not occur after terracing when hydrographs reflected the stepwisedraining of each terrace through the pipe outlet. After an initial 2-year period of terrace stabilization, suspended-sediment yield in runoff decreased significantly as a function of runoff. This result was expected because terracing decreased runoff energy, and because terrace ponding allowed time for sediment redeposition. Nitrate plus nitrite yields increased proportionally throughout the range of runoff during the post-terracing period relative to the pre- terracing period. After terracing, a combination of increased soil contact time and increased nitrification caused by wetter soils is believed to have increased nitrate concentrations in runoff. No significant change was found in yields of total nitrogen, ammonia plus organic nitrogen, or total phosphorus relative to runoff before and after terracing. Limited data suggest that fine-sediment particles (less than 0.62 micrometers in diameter), which continued to be discharged from the site, transported most of the phosphorus. Terracing did not significantly change the quantity of recharge to the carbonate aquifer. The mean annual water-table altitude did not change after terracing. Nitrate concentrations of ground water increased significantly at four of the site wells after terracing, probably because of increased contact time of the recharge with nutrient-rich soils in ponded terrace water. Qualitative evidence indicates that large decreases in nutrient requirements and nitrogen applications because of a crop change from corn to alfalfa upgradient of two site wells resulted in either no detectable change or a significant decrease in nitrate concentrations of ground water after terracing.

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USGS1997

Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania: Effects of nutrient management on quality of surface runoff and ground water at a small carbonate-rock site near Ephrata, Pennsylvania, 1984-90

The U.S. Geological Survey and the Pennsylvania Department of Environmental Protection conducted a study from 1984 to 1990 to determine theeffects of the implementation and practice of nutrient management [an agricultural best-management practice (BMP)] on the quality of surface runoff and ground water at a 55-acre crop and livestock farm in carbonate terrain nearEphrata, Pa. Implementation of nutrient management at Field-Site 2 resulted in application decreases of 33 percent for nitrogen and 29 percent for phosphorus. There wereno significant changes in nitrogen or phosphorusloads for a given amount of runoff from the pre-BMP to the post-BMP periods. However, less than 2 percent of the applied nutrients weredischarged with runoff throughout the study period.After the implementation of nutrient management, statistically significant decreases in concentrations of nitrate in ground-water samples occurred at threeof the four wells monitored throughout the pre- and post-BMP periods. The largest decreases in nitrate concentrations occurred at wells where samples hadthe largest nitrate concentrations prior to nutrient management. Changes in nitrogen applications to the contributing areas of five wells were correlated with nitrate concentrations of the well water. The correlations between the timing and amount of applied nitrogen and changes in ground-water quality met the four conditions that are characteristic of a cause-effect relation: an association, consistency, responsiveness, and a mechanism. Changes in ground-water nitrate concentrations lagged behind changes in loading of nitrogen fertilizers (primarily manure) by approximately 4 to 19 months.

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USGS1997

Water resources of Indiana County, Pennsylvania

Indiana County, west-central Pennsylvania, is a major producer of coal and natural gas. Water managers and residents are concerned about the effects of mining and natural gas exploration on the surface- and ground-water resources of the county. This study assesses the quality and quantity of water in Indiana County. Ground- and surface-water sources are used for public supplies that serve 61 percent of the total population of the county. The remaining 39 percent of the population live in rural areas and rely on cisterns and wells and springs that tap shallow aquifers. Most of the county is underlain by rocks of Middle to Upper Pennsylvanian age. From oldest to youngest, they are the Allegheny Group, the Glenshaw Formation, the Casselman Formation, and the Monongahela Group. Almost all the coals mined are in the Allegheny Group and the Monongahela Group. Ground water in Indiana County flows through fractures in the rock. The size and extent of the fractures, which are controlled by lithology, topography, and structure, determine the sustained yield of wells. Topography has a significant control over the yields of wells sited in the Allegheny Group. Properly sited wells in the Glenshaw Formation may have yields adequate for municipal, commercial, or industrial uses. The Casselman Formation yields adequate amounts of water for domestic use. Yield of the Monongahela Group is small, and the water may not be of suitable quality for most uses. Yields of hilltop wells may be marginal, but valley wells may yield sufficient amounts for large-volume users. Data on the other rock units are sparse to nonexistent. Few wells in the county yield more than 40 gallons per minute. Most of the wells that do are in valleys where alluvial deposits are extensive enough to be mapable. Short-term water-level fluctuations are variable from well to well. Seasonal water-level fluctuations are controlled by time of year and amount of precipitation. The quality of water from the Casselman Formation, Glenshaw Formation, and Allegheny Group tends to be hard and may have concentrations of iron and manganese that exceed the U.S. Environmental Protection Agency Secondary Maximum Contaminant Levels of 0.3 milligrams per liter and 0.05 milligrams per liter, respectively. Ground water from the Glenshaw Formation is less mineralized than ground water from the Allegheny Group. Concentrations of minerals in water from the Casselman Formation are between those in water from the Glenshaw Formation and the Allegheny Group. Water from wells on hilltops has lower concentrations of dissolved solids than water from wells on hillsides. Water from valley wells is the most mineralized. Nearly half the springs tested yield water that is low in pH and dissolved solids; this combination makes the water chemically aggressive. The 7-day, 10-year low-flow frequencies for 26 unregulated surface-water sites ranged from 0.0 to 0.19 cubic feet per second per square mile. The presence of coal mines and variations in precipitation were probably the principal factors affecting flow duration on Blacklick Creek (site 28) during 1953-88. Sustained base flows of regulated streams such as Blacklick Creek generally were larger than those of unregulated streams as a result of low-flow augmentation. The annual water loss in streamflow as a result of evapotranspiration, diversion, seepage to mines, and seepage to the ground-water system was determined at four sites (sites 8, 9, 17, and 28) and ranged from 35 to 53 percent. The highest concentrations of dissolved solids, iron, manganese, aluminum, zinc, and sulfate were measured mostly in streams in central and southern Indiana County, where active and abandoned coal mines are the most numerous. Streamflow was measured during low flow in two small basins; one basin almost completely deep mined (Cherry Run) and one basin unmined (South Branch Plum Creek). The measurements showed a con

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USGS1997

Hydrogeologic investigation of the Malvern TCE Superfund Site, Chester County, Pennsylvania

The Malvern TCE Superfund Site, a former solvent recycling facility that now stores and sells solvents, consists of a plant and disposal area, which are approximately 1,900 ft (feet) apart. The site is underlain by an unconfined carbonate bedrock aquifer in which permeability has been enhanced in places by solution. Water levels respond quickly to precipitation and show a similar seasonal variation, response to precipitation, and range of fluctuation. The altitude of water levels in wells at the disposal area is nearly identical because of the small hydraulic gradient. A comparison of water-table maps for 1983, 1993, and 1994 shows that the general shape of the water table and hydraulic gradients in the area have remained the same through time and for different climatic conditions. The plant area is underlain by dolomite of the Elbrook Formation. The dolomite at the plant area does not yield as much water as the dolomite at the disposal area because it is less fractured, and wells penetrate few water-bearing fractures. Yields of nine wells at the plant area range from 1 to 200 gal/min (gallons per minute); the median yield is 6 gal/min. Specific capacities range from 0.08 to 2 (gal/min)/ft (gallons per minute per foot). Aquifer tests were conducted in two wells; median transmissivities estimated from the aquifer-test data ranged from 528 to 839 feet squared per day. Maximum concentrations of volatile organic compounds (VOC's) in ground water at the plant area in 1996 were 53,900 ug/L (micrograms per liter) for trichloroethylene (TCE), 7,110 ug/L for tetrachloroethylene (PCE), and 17,700 ug/L for 1,1,1-trichloroethane (TCA). A ground-water divide is located between the plant area and the disposal area. Ground-water withdrawal for dewatering the Catanach quarry has caused a cone of depression in the water-table surface that reaches to the plant area. From the plant area, ground water flows 1.2 miles to the northeast and discharges to the Catanach quarry. The regional hydraulic gradient between the plant and the Catanach quarry is 0.019. Concentrations of VOC's in water from wells drilled northeast and donwgradient of the plant property boundary are one to two orders of magnitude less than concentrations in water from wells less than 100 ft away at the plant. A capture-zone analysis was performed for two wells at the plant area. The analysis showed that pumping well CC-19 at 20 gal/min would be sufficient to capture all ground-water flow from the plant area. Although water from other wells at the plant site contains higher concentrations of VOC's than water from well CC-19, pumping well CC-19 would induce the flow of water with higher concentrations of VOC's; however, pumping well CC-19 might causes VOC's to move lower into the aquifer. The disposal area is underlain by the Ledger Dolomite. The dolomite at the disposal area is much more fractured than the dolomite at the plant area. Although many of the fractures are filled or partially filled with clay, the dolomite at the disposal area yields more water than the dolomite at the plant area. Yields of eight wells at the disposal area range from 15 to more than 200 gal/min; the median yield is greater than 100 gal/min. Specific capacities range from 2 to 280 (gal/min)/ft. Aquifer tests were conducted in two wells; estimated transimissivities were 34,900 and 56,300 feet squared per day. Concentrations of VOC's in ground water are lower at the disposal area than at the plant area. Water samples collected from wells at the disposal area in 1996 had maximum concentrations of TCE of 768 ug/L, PCE of 111 ug/L, and TCA of 108 ug/L. These concentrations are lower than concentrations in water samples collected before cleanup of drums in the disposal area was completed in 1984. Ground water from the disposal area flows south-southeast toward Valley Creek. The hydraulic gradient between the disposal area and Valley Creek is 0.001. A well-defined plume of VOC’s in ground water extends downgradient from the disposal area toward Valley Creek. A comparison of data from 1995 to 1996 with data from 1981 to 1984 shows that concentrations of TCE, PCE, and TCA in water from most off-site wells have decreased and that water from fewer wells contains detectable concentrations of those compounds. A capture-zone analysis was performed for three wells at the disposal area. The analysis showed that pumping wells CC-16, CC-17, and CC-18 at a combined rate of 270 gal/min would form a capture zone ranging from approximately 443 to 477 ft wide at a distance 500 ft upgradient from the center of the pumping wells. Pumping wells CC-16 and CC-17 together at a combined rate of 172 gal/min would form a capture zone ranging from approximately 172 to 400 ft wide at a distance 500 ft upgradient from the center of the pumping wells.

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USGS1997

Surface-water quality changes after 5 years of nutrient management in the Little Conestoga Creek headwaters, Pennsylvania, 1989-91

A 5.82-square-mile drainage basin in the headwaters of the Little Conestoga Creek in Lancaster County, Pa., was investigated from October 1989 through September 1991 as part of a longer-term effort to determine the effects of nutrient management on surface-water quality. A previous investigation found no statistical evidence that implementation of nutrient management from 1986 to 1989 affected water quality. Basin land use is 68 percent agriculture and includes all or part of 51 farms. Agricultural land under nutrient management ranged from 55 percent in 1989 to 80 percent in 1991. Nitrate nitrogen, the dominant nonpoint-source contaminant, averaged about 7.5 milligrams per liter in base flow. Implementation of nutrient management on 90 percent of applicable land in a 1.42-square-mile subbasin resulted in a 7 percent decrease in nitrogen applications from before nutrient management. Recognizing that some uncertainty exists in the nutrient-application data, the decrease consisted of a 44-percent decrease in commercial fertilizer nitrogen combined with a 3-percent increase in manure nitrogen applications. Manure accounted for 83 percent of the applied nitrogen. Amounts of nitrate nitrogen in the top 4 feet of soil ranged from 43 to 315 pounds per acre in the subbasin and were not substantially reduced from before nutrient management. Statistical analysis of nutrient and suspended-sediment concentrations detected few significant step trends in water quality in a comparison with water quality before nutrient management. A decrease in base-flow concentrations of dissolved ammonium and suspended sediment was detected at a site draining a 1.43-square-mile subbasin with 40-percent implementation of nutrient-management plans. An increase in base-flow concentrations of suspended sediment was detected at a site draining the 1.42-square-mile subbasin with 90-percent implementation. A comparison of the dissolved nitrate plus nitrite in base-flow relations between paired subbasins detected no change from 1984-86 (before nutrient management) to 1989-91. Mean concentrations in stormflow were not reduced significantly from 1984-86 to 1989-91. Data collected during the entire 1986-91 nutrient-management period suggest a reduction in nitrogen input as large as the 30-percent reduction recorded from 1986-89 is needed to effect a 0.5-milligram-per-liter decrease in dissolved nitrate plus nitrite.

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USGS1997

Results of borehole geophysical logging and aquifer-isolation tests conducted in the John Wagner and Sons, Inc. former production well, Ivyland, Pennsylvania

A suite of borehole geophysical logs and heat-pulse-flowmeter measurements run in the former production well at the John Wagner and Sons, Inc. plant indicate two zones of borehole flow. In the upper part of the well, water enters the borehole through a fracture at 90 ft (feet) below floor level, moves upward, and exits the borehole through a fracture at 72 ft below floor level. Water also enters the borehole through fractures at 205-213, 235, and 357 ft below floor level; moves downward; and exits the borehole through fractures at 450-459, 468-470, and 483-490 ft below floor level. Five zones were selected for aquifer-isolation (packer) tests on the basis of borehole geophysical logs. The zones were isolated using a straddle-packer assembly. The lowermost three zones (below 248, 223 to 248, and 198 to 223 ft below floor level) were hydraulically isolated from zones above and below. Specific capacities were 0.12, 0.034, and 0.15 gallons per minute per foot, respectively. The hydrograph from zone 2 (223 to 248 ft below floor level) showed interference from a nearby pumping well. For the upper two zones (81 to 106 and 57 to 81 ft below floor level), similar drawdowns in the isolated zone and the zones above and below the isolated zone indicate that these fractures are hydraulically connected outside the borehole in the unconfined part of the Stockton Formation. The specific capacity of zones 4 and 5 are similar—0.82 and 0.61, respectively.

Pennsylvania↗

USGS1997

Metals, pesticides, and semivolatile organic compounds in sediment in Valley Forge National Historical Park, Montgomery County, Pennsylvania

The Schuylkill River flows through Valley Forge National Historical Park in Lower Providence and West Norriton Townships in Montgomery County, Pa. The concentration of selected metals, pesticides, semivolatile organic compounds, and total carbon in stream-bottom sediments from Valley Forge National Historical Park were determined for samples collected once at 12 sites in and around the Schuylkill River. Relatively low concentrations of arsenic, chromium, copper, and lead were detected in all samples. The concentrations of these metals are similar to concentrations in other stream-bottom sediment samples collected in the region. The concentrations of iron, manganese, and zinc were elevated in samples from four sites in the Schuylkill River, and the concentration of mercury was elevated in a sample from an impoundment along the river. The organophosphorus insecticide diazinon was detected in relatively low concentrations in half of the 12 samples analyzed. The organo-chlorine insecticide DDE was detected in all 12 samples analyzed; dieldrin was detected in 10 samples, chlordane, DDD, and DDT were detected in 9 samples, and heptachlor epoxide was detected in one sample. The concentrations of organo-chlorine and organophosphorus insecticides were relatively low and similar to concentrations in samples collected in the region. Detectable concentrations of 17 semivolatile organic compounds were measured in the 12 samples analyzed. The most commonly detected compounds were fluoranthene, phenanthrene, and pyrene. The maximum concentration detected was 4,800 micrograms per kilogram of phenanthrene. The highest concentrations of compounds were detected in Lamb Run, a small tributary to the Schuylkill River with headwaters in an industrial corporate center. The concentration of compounds in the Schuylkill River below Lamb Run is higher than the Schuylkill River above Lamb Run, indicating that sediment from Lamb Run is increasing the concentration of semivolatile organic compounds in sediment from the Schuylkill River. Concentrations of semivolatile organic compounds are lower in sediment from the Schuylkill River below Myer's Run than above Myer's Run because of the addition of relatively clean sediment from Myer's Run. Samples collected from the floodplain, impounding basin, and wetland along the Schuylkill River contained the lowest concen-trations of semivolatile organic compounds. Detectable concentrations of polychlorinated biphenyls (PCB's) were measured in 11 of the 12 samples analyzed. The maximum PCB concentration was 37 micrograms per kilogram. Sediment samples from Lamb Run contained the highest concentrations of semivolatile organic compounds and PCB's.

Pennsylvania↗

USGS1997

Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania: A summary report, 1982-90

Pipe-outlet terracing was effective in reducing sediment losses from a field site, but total nitrogen and phosphorus losses with runoff were not significantly different before and after terracing. Median concentrations of dissolved nitrate in several ground-water sampling locations increased after terrace installation. Dissolved nitrate concentrations in ground water decreased significantly after nutrient-management implementation. Findings indicate that agricultural-management practices to improve water quality are most effective if their overall design effects on surface- and ground-water systems are considered in their design.

Pennsylvania↗