USGS Science⌕ Search

Geology topics

Research about Maryland, Pennsylvania

Source-linked reports with geographic coverage including Maryland, Pennsylvania.

At least 19 recordsLinked to original sources
USGS2018

Reestablishing a host–affiliate relationship: Migratory fish reintroduction increases native mussel recruitment

Co‐extirpation among host–affiliate species is thought to be a leading cause of biodiversity loss worldwide. Freshwater mussels (Unionida) are at risk globally and face many threats to survival, including limited access to viable host fish required to complete their life history. We examine the relationship between the common eastern elliptio mussel ( Elliptio complanata ) and its migratory host fish the American eel ( Anguilla rostrata ), whose distribution in the Chesapeake Bay watershed is limited, in part, by dams. We examined population demographics of E. complanata across locations in the Chesapeake Bay watershed, primarily in the Susquehanna River in the absence of American eels, and conducted experimental restocking of eels to assess potential impacts on mussel recruitment. Compared to surveys completed ~20 yr prior, E. complanata could be experiencing declines at several historically abundant sites. These sites also had extremely limited evidence of recruitment. Restoration of host fish improved recruitment, but results were not equivalent between stocking sites, indicating that host reintroduction alone may not be fully effective in reestablishing mussel populations. One site where eels were introduced (Pine Creek, Tioga County, Pennsylvania, USA) experienced an increase from 0 juveniles found during quantitative surveys prior to eel stocking to 151 (21% of individuals collected during quantitative surveys) E. complanata juveniles found four years after stocking. A second site (Buffalo Creek, Union County, Pennsylvania) experienced a more moderate increase from 2 to 7 juveniles found during 2010 and 2014 quantitative surveys, respectively. Continued examination of other potential interacting factors affecting recruitment, including water quality or habitat conditions, is necessary to target favorable sites for successful restoration.

Maryland, Pennsylvania↗
USGS2015

Sediment transport and capacity change in three reservoirs, Lower Susquehanna River Basin, Pennsylvania and Maryland, 1900-2012

The U.S. Geological Survey (USGS) has conducted numerous sediment transport studies in the Susquehanna River and in particular in three reservoirs in the Lower Susquehanna River Basin to determine sediment transport rates over the past century and to document changes in storage capacity. The Susquehanna River is the largest tributary to Chesapeake Bay and transports about one-half of the total freshwater input and substantial amounts of sediment and nutrients to the bay. The transported loads are affected by deposition in reservoirs (Lake Clarke, Lake Aldred, and Conowingo Reservoir) behind three hydropower dams. The geometry and texture of the deposited sediments in each reservoir upstream from the three dams has been a subject of research in recent decades. Particle size deposition and sediment scouring processes are part of the reservoir dynamics. A Total Maximum Daily Load (TMDL) for nitrogen, phosphorus, and sediment was established for Chesapeake Bay to attain water-quality standards. Six states and the District of Columbia agreed to reduce loads to the bay and to meet load allocation goals for the TMDL. The USGS has been estimating annual sediment loads at the Susquehanna River at Marietta, Pennsylvania (above Lake Clarke), and Susquehanna River at Conowingo, Maryland (below Conowingo Reservoir), since the mid-1980s to predict the mass balance of sediment transport through the reservoir system. Using streamflow and sediment data from the Susquehanna River at Harrisburg, Pennsylvania (upstream from the reservoirs), from 1900 to 1981, sediment loads were greatest in the early to mid-1900s when land disturbance activities from coal production and agriculture were at their peak. Sediment loads declined in the 1950s with the introduction of agricultural soil conservation practices. Loads were dominated by climatic factors in the 1960s (drought) and 1970s (very wet) and have been declining since the 1980s through 2012. The USGS developed a regression equation to predict the sediment scour load for daily mean streamflows greater than 300,000 cubic feet per second for the Lower Susquehanna River reservoirs. A compilation of data from various sources produced a range in total sediment transported through the reservoir system and allowed for apportioning to source (watershed or scour) for various streamflows. In 2011, Conowingo Reservoir was estimated to be about 92 percent of sediment storage capacity. Since construction of Conowingo Dam in 1929 through 2012, approximately 470 million tons of sediment was transported down the Susquehanna River into the reservoir system, approximately 290 million tons were trapped, and approximately 180 million tons were transported to Chesapeake Bay. Spatial and estimated total sand deposition in Conowingo Reservoir based on historical sediment cores indicated continued migration of sand downgradient toward the dam and the winnowing of silts and clays near the dam due to scour.

Maryland, Pennsylvania↗
USGS2014

The pre-Cambrian igneous rocks of eastern Pennsylvania and Maryland

The Blue Ridge and Piedmont geomorphic provinces, topographically distinct but geologically a unit, extend southwestward across eastern Pennsylvania and central Maryland, in a belt with an average width in these States of some 50 miles. In these provinces are exposed the crystalline formations of the Atlantic belt. Gneisses (with sporadic interbedded graphitic schist and marble), quartz-schist, crystalline limestone, and scnlsts, constitute the pre-Cambrian sedimentary series which has been folded, overturned, and overthrust with faulting, to the northwest.

Maryland, Pennsylvania↗
USGS2003

Development of regional curves of bankfull-channel geometry and discharge for streams in the non-urban, Piedmont Physiographic Province, Pennsylvania and Maryland

Stream-restoration projects utilizing natural stream designs frequently are based on the bankfull-channel characteristics of stream reaches that can accommodate streamflow and sediment transport without excessive erosion or deposition and lie within a watershed that has similar runoff characteristics. The bankfull channel at an ungaged impaired site or reference reach is identified by use of field indicators and is confirmed with tools such as regional curves. Channel dimensions were surveyed at 14 streamflow-measurement stations operated by the U.S. Geological Survey (USGS) in the Gettysburg-Newark Lowland Section, Piedmont Lowland Section, and the Piedmont Upland Section of the Piedmont Physiographic Province in Pennsylvania and Maryland. From the surveyed channel dimensions, regional curves were developed from regression analyses of the relations between drainage area and the cross-sectional area, mean depth, width, and streamflow of the bankfull channel at these sites. Bankfull cross-sectional area and bankfull discharge have the strongest relation to drainage area as evidenced by R 2 values of 0.94 and 0.93, respectively. The relation between bankfull crosssectional area and drainage area has a p-value of less than 0.001; no p-value is presented for the relation between bankfull discharge and drainage area because of a non-normal residual distribution. The relation between bankfull width and drainage area has an R 2 value of 0.80 and a p-value of less than 0.001 indicating a moderate linear relation between all stations. The relation between bankfull mean depth and drainage area, with an R 2 value of 0.72 and a p-value of less than 0.001, also indicates a moderate linear relation between all stations. The concept of regional curves can be a valuable tool to support efforts in stream restoration. Practitioners of stream restoration need to recognize it as such and realize the limitations. The small number of USGS streamflow-measurement stations available for analysis is a major limiting factor in the strength of the results of this investigation, as is the inherent problem of directly associating streamflow-measurement station data to geomorphic analysis of a stream reach. Subjective selection criteria may have unnecessarily eliminated streamflow-measurement stations that could have been included in the regional curves and (or) added those that may belong within a different region. A bankfull discharge with a recurrence interval within the 1- to 2-year range commonly is used as a criterion for the confirmation of the bankfull stage at each streamflow-measurement station. Many researchers accept this range for recurrence interval of the bankfull discharge; however, literature provides contradictory evidence.

Maryland, Pennsylvania↗
USGS2002

Geohydrology and ground-water quality, Big Elk Creek Basin, Chester County, Pennsylvania, and Cecil County, Maryland

A study of ground-water quantity and quality was conducted in the Big Elk Creek Basin, a rural area undergoing rapid growth. The 79.4-square mile study area is in the Piedmont Physiographic Province and is underlain almost entirely by crystalline rocks. Most of the basin in Pennsylvania is underlain by Wissahickon Schist, a fractured crystalline- rock aquifer. Yields of wells in the Wissahickon Schist range from 5 to 200 gal/min (gallons per minute); the median yield is 15 gal/min. Specific capacity ranges from 0.03 to 15 (gal/min)/ft (gallons per minute per foot) of drawdown; the median specific capacity is 0.4 (gal/min)/ft. Recharge to the basin occurs by infiltration of precipitation, and ground water discharges locally to streams. The median annual ground-water discharge to streams (base flow) for 1933-99 was 10.79 in. (inches) or 0.518 (Mgal/d)/mi 2 (million gallons per day per square mile), which was 63 percent of the median annual streamflow. The median annual ground-water discharge to streams ranged from 5.32 in. or 0.255 (Mgal/d)/mi 2 in 1966 to 17.98 in. or 0.863 (Mgal/d)/mi 2 in 1972. Estimated ground-water availability ranges from 0.127 to 0.535 (Mgal/d)/mi 2 , depending on the estimation method used. Annual water budgets were calculated for the Big Elk Creek Basin for 1998-99. The 1998-99 average annual streamflow was 15.38 in., change in ground-water storage was an increase of 1.32 in., ground-water exports were 0.03 in., and estimated evapotranspiration (ET) was 30.5 in. Despite a 12.27-in. difference in precipitation between 1998 and 1999, the percentage of precipitation as ET (65.6 and 64 percent, respectively) is similar. Estimated average annual recharge for 1998-99 was 12.12 in. [0.580 (Mgal/d)/mi 2 ]. For this study, water samples from 20 wells in the Big Elk Creek Basin were collected for analysis for inorganic constituents and pesticides. In addition, data were available from 44 additional wells. Major ions, in order of decreasing concentration, based on median concentrations for the Wissahickon Schist, are silica, calcium, chloride, sodium, sulfate, magnesium, and potassium. The Wissahickon Schist and Peters Creek Schist have similar water types; ground water from serpentinite, the basal unit of the Baltimore Mafic Complex that straddles the Pennsylvania-Maryland border, is distinctly different. For the Wissahickon Schist and Peters Creek Schist, no cation is predominant; calcium, magnesium, and sodium are in nearly equal concentrations expressed in milliequivalents per liter. Bicarbonate is the dominant anion. Water from serpentinite is of the magnesium bicarbonate type; magnesium is the dominant cation, and bicarbonate is the dominant anion. Water from 2 percent of sampled wells exceeded the U.S. Environmental Protection Agency (USEPA) secondary maximum contaminant level (SMCL) for total dissolved solids. None of the chloride or sulfate concentrations exceeded the USEPA SMCL. Water from 10 percent of sampled wells exceeded the USEPA maximum contaminant level (MCL) of 10 mg/L (milligrams per liter) nitrate as nitrogen. All of those wells are in the Wissahickon Schist. The median concentration of nitrate in water samples from the Wissahickon Schist was 3.6 mg/L, and the maximum concentration was 36 mg/L. Except for iron and manganese, metals and other trace inorganic constituents do not appear to pose a water-quality problem. Fourteen percent of water samples analyzed for iron and 29 percent of water samples analyzed for manganese exceeded the USEPA SMCL's. The median activity of radon-222 for all formations was 2,400 pCi/L (picoCuries per liter). The median activity for water from 35 wells sampled in the Wissahickon Schist in the Big Elk Creek Basin was 2,500 pCi/L. Water from 94 percent of sampled wells exceeded the proposed USEPA MCL of 300 pCi/L, and water from 25 percent of sampled wells exceeded proposed USEPA alternate MCL of 4,000 pCi/L. In addition to the 20 wells sampled for pesticides for this study, data were available for 20 other wells sampled for pesticides. The most commonly detected pesticides in the Big Elk Creek Basin are deethyl atrazine (71 percent of sampled wells), atrazine (35 percent of sampled wells), metolachlor (32 percent of sampled wells), carbaryl (19 percent of sampled wells), picloram (14 percent of sampled wells), simazine (13 percent of sampled wells), and carbofuran (11 percent of sampled wells). Most concentrations are extremely low and are in the parts per trillion range. Concentrations of pesticides detected did not exceed USEPA MCL’s. Out of 43 volatile organic compounds analyzed, only 4 were detected—chloroform, total phenols, tert-butyl methyl ether (MTBE), and toluene. None of the concentrations exceeded USEPA MCL’s.

Maryland, Pennsylvania↗
USGS1997

Water-quality assessment of the Lower Susquehanna River Basin, Pennsylvania and Maryland: Design and implementation of water-quality studies, 1992-95

From 1992 through 1995, nearly 1,200 water-quality samples from about 500 sites were collected, processed, and analyzed for the U.S. Geological Survey's (USGS) National Water-Quality Assessment (NAWQA) Program in the Lower Susquehanna River Basin in Pennsylvania and Maryland. Sites were selected and samples were collected for 28 integrated water-quality studies designed to provide a comprehensive and nationally consistent description of current water-quality conditions, to begin to identify trends in water quality, and to determine the major factors that affect observed water quality. To achieve this, stream-water, ground-water, streambed-sediment, and biota samples were collected, and habitat assessments were conducted at selected data-collection sites. This report discusses the water-quality study design, site-selection strategy, and implementation steps used to obtain water-quality and related data. Methods employed to collect, process, and analyze samples, characterize sites, and assess habitat are described. A comprehensive list of all sites employed in these studies and their characteristics is provided. Sample analyses conducted for the water-quality studies described in this report, including nutrients, pesticides, major ions, volatile organic compounds (VOC's), and trace elements, as well as measured or observed physical properties and habitat characteristics, also are listed.

Maryland, Pennsylvania↗
USGS1997

Sediment deposition in Lake Clarke, Lake Aldred, and Conowingo Reservoir, Pennsylvania and Maryland, 1910-93

The Susquehanna River carries a significant amount of the sediment and the nutrient load transported to the Chesapeake Bay. Three large hydroelectric dams are located near the mouth of the Susquehanna River. The three dams and associated reservoirs are Safe Harbor (Lake Clarke) and Holtwood (Lake Aldred) in southern Pennsylvania and Conowingo (Conowingo Reservoir) in northern Maryland. Two of these reservoirs, Lakes Clarke and Aldred, have reached a state of equilibrium with sediment transport in the river. The third, Conowingo Reservoir, continues to accumulate sediment as well as particulate organic nitrogen and particulate phosphorus. Bottom-elevation surveys of Conowingo Reservoir made in 1959, 1990, and 1993 indicate that the reservoir will reach equilibrium with sediment transport of the river during the next 10 to 20 years. Data collected from 1985-89 indicate that the Susquehanna River transports about 1,780 million pounds of sediment, 147 million pounds of nitrogen, and 5.1 million pounds of phosphorus to the Chesapeake Bay during a year of normal streamflow. Once equilibrium is reached in the Conowingo Reservoir, these loads may increase to levels currently transported by the river to the reservoirs, about 6,600 million pounds of sediment, 153 million pounds of nitrogen, and 9.1 million pounds of phosphorus per year. These higher loads may effect progress made on reducing nutrient loads and should be considered when planning future programs.

Maryland, Pennsylvania↗
USGS1997

Identification of potential water-bearing zones by the use of borehole geophysics in the vicinity of Keystone Sanitation Superfund Site, Adams County, Pennsylvania, and Carroll County, Maryland

Between April 23, 1996, and June 21, 1996, the U.S. Environmental Protection Agency contracted Haliburton-NUS, Inc., to drill four clusters of three monitoring wells near the Keystone Sanitation Superfund Site. The purpose of the wells is to allow monitoring and sampling of shallow, intermediate, and deep waterbearing zones for the purpose of determining the horizontal and vertical distribution of any contaminated ground water migrating from the Keystone Site. Twelve monitoring wells, ranging in depth from 50 to 397.9 feet below land surface, were drilled in the vicinity of the Keystone Site. The U.S. Geological Survey conducted borehole-geophysical logging and determined, with geophysical logs and other available data, the ideal intervals to be screened in each well. Geophysical logs were run on four intermediate and four deep wells, and a caliper log only was run on shallow well CL-AD-173 (HN-1S). Interpretation of geophysical logs and existing data determined the placement of screens within each borehole.

Maryland, Pennsylvania↗
USGS1997

Changes in bottom-surface elevations in three reservoirs on the lower Susquehanna River, Pennsylvania and Maryland, following the January 1996 flood — Implications for nutrient and sediment loads to Chesapeake Bay

The Susquehanna River drains about 27,510 square miles in New York, Pennsylvania, and Maryland, contributes nearly 50 percent of the freshwater discharge to the Chesapeake Bay, and contributes nearly 66 percent of the annual nitrogen load, 40 percent of the phosphorus load, and 25 percent of the suspended-sediment load from non-tidal parts of the Bay during a year of average streamflow. A reservoir system formed by three hydroelectric dams on the lower Susquehanna River is currently trapping a major part of the phosphorus and suspended-sediment loads from the basin and, to a lesser extent, the nitrogen loads. In the summer of 1996, the U. S. Geological Survey collected bathymetric data along 64 cross sections and 40 bottom-sediment samples along 14 selected cross sections in the lower Susquehanna River reservoir system to determine the remaining sediment-storage capacity, refine the current estimate of when the system may reach sediment-storage capacity, document changes in the reservoir system after the January 1996 flood, and determine the remaining nutrient mass in Conowingo Reservoir. Results from the 1996 survey indicate an estimated total of 14,800,000 tons of sediment were scoured from the reservoir system from 1993 (date of previous bathymetric survey) through 1996. This includes the net sediment change of 4,700,000 tons based on volume change in the reservoir system computed from the 1993 and 1996 surveys, the 6,900,000 tons of sediment deposited from 1993 through 1996, and the 3,200,000 tons of sediment transported into the reservoir system during the January 1996 flood. The January 1996 flood, which exceeded a 100-year recurrence interval, scoured about the same amount of sediment that normally would be deposited in the reservoir system during a 4- to 6-year period. Concentrations of total nitrogen in bottom sediments in the Conowingo Reservoir ranged from 1,500 to 6,900 mg/kg (milligrams per kilogram); 75 percent of the concentrations were between 3,000 and 5,000 mg/kg. About 96 percent of the concentrations of total nitrogen consisted of organic nitrogen. Concentrations of total phosphorus in bottom sediments ranged from 286 to 1,390 mg/kg. About 84 percent of the concentrations of total phosphorus were comprised of inorganic phosphorus. The ratio of concentrations of plant-available phosphorus to concentrations of total phosphorus ranged from 0.6 to 3.5 percent; ratios generally decreased in a downstream direction. About 29,000 acre-feet, or 42,000,000 tons, of sediment can be deposited before Conowingo Reservoir reaches sediment-storage capacity. Assuming the average annual sediment-deposition rate remains unchanged and no scour occurs due to floods, the reservoir system could reach sediment-storage capacity in about 17 years. The reservoir system currently is trapping about 2 percent of the nitrogen, 45 percent of the phosphorus, and 70 percent of the suspended sediment transported by the river to the upper Chesapeake Bay. Once the reservoir reaches sediment-storage capacity, an estimated 250-percent increase in the current annual loads of suspended sediment, a 2-percent increase in the current annual loads of total nitrogen, and a 70-percent increase in the current annual loads of total phosphorus from the Susquehanna River to Chesapeake Bay can be expected. If the goal of a 40-percent reduction in controllable phosphorus load from the Susquehanna River Basin is met before the reservoirs reach sediment-storage capacity, the 40-percent reduction goal will probably be exceeded when the reservoir system reaches sediment-storage capacity.

Maryland, Pennsylvania↗
USGS1997

Nitrate in ground water and stream base flow in the lower Susquehanna River Basin, Pennsylvania and Maryland

High concentrations of nitrate in both ground and surface water have been identified as a significant water-quality issue in the Lower Susquehanna River Basin. This report uses data collected by the National Water Quality Assessment (NAWQA) Program in the basin and compares nitrate concentrations found in ground water and surface water on both a spatial and temporal basis and relates nitrate concentrations to land use. Nitrate concentrations in the Lower Susquehanna River Basin in Pennsylvania and Maryland were higher in ground water than in surface water in agricultural areas underlain by carbonate bedrock and agricultural areas underlain by crystalline bedrock. Nitrate concentrations were higher in surface water than in ground water in urban areas underlain by carbonate bedrock. Nitrate concentrations also were higher in surface water than ground water in both agricultural and forested areas underlain by sandstone and shale. Nitrate concentrations in ground water vary in areas with different land use and bedrock type. Ground-water nitrate concentrations were highest in agricultural areas underlain by carbonate bedrock, where 45 percent of the samples exceeded the U.S. Environmental Protection Agency (USEPA) Maximum Contaminant Level (MCL) of 10 mg/L (milligrams per liter as N). Waters from 36 percent of the wells in agricultural areas underlain by crystalline bedrock also had nitrate concentrations greater than 10 mg/L. Nitrate concentrations in water from wells in urban areas underlain by carbonate bedrock and in forested and agricultural areas underlain by sandstone and shale seldom exceeded the MCL. Nitrate concentrations were generally higher in surface water in areas underlain by carbonate bedrock than in areas underlain by noncarbonate bedrock; however, when an agricultural area underlain by carbonate bedrock and an agricultural area underlain by sandstone and shale with similar manure application rates were compared, nitrate concentrations in surface water were not significantly different. A comparison of three agricultural areas underlain by carbonate bedrock shows that the manure application rate is strongly correlated with nitrate concentration. Nitrate concentrations in stream base flow at seven sites where samples were collected throughout the year were commonly higher in the winter months than in the summer months. A statistically significant correlation between streamflow and nitrate concentration existed for six of the seven sites, indicating that seasonal variability in precipitation may be the cause of some of the seasonal variation in concentration. Other possible explanations for this variation include the seasonal cycle in plant uptake of nitrogen and seasonal fluctuations in uptake of nitrate by algae in streams. Because no information was available about the traveltime for ground water, interpretation of this temporal variation was not conclusive. Estimates of base-flow loads and yields of nitrate showed that agricultural areas underlain by carbonate bedrock provide the highest yield of nitrate when compared with the other areas studied. Agricultural areas underlain by sandstone and shale and crystalline bedrock also provide large amounts of nitrate to the river. The large amount of nitrate in the water from these areas cause a significant increase in nitrate loads transported by the Susquehanna River to the Chesapeake Bay. Urban areas underlain by carbonate bedrock had a high yield of nitrate but comprise such a small part of the basin that the nitrate load from these areas was small. In contrast, forested areas underlain by sandstone and shale bedrock had low base-flow nitrate yields, but these areas comprise a large percentage of the basin, making the overall nitrate load from these areas high.

Maryland, Pennsylvania↗
USGS1997

Water-quality assessment of the Lower Susquehanna River Basin, Pennsylvania and Maryland: sources, characteristics, analysis and limitations of nutrient and suspended-sediment data, 1975-90

This report describes analyses of available information on nutrients and suspended sediment collected in the Lower Susquehanna River Basin during water years 1975-90. Most of the analyses were applied to data collected during water years 1980-89. The report describes the spatial and temporal availability of nutrient and suspended-sediment data and presents a preliminary concept of the spatial and temporal patterns of concentrations and loads within the basin. Where data were available, total and dissolved forms of nitrogen and phosphorus species from precipitation, surface water, ground water, and springwater, and bottom material from streams and reservoirs were evaluated. Suspended-sediment data from streams also were evaluated. The U.S. Geological Survey National Water Information System (NWIS) database was selected as the primary database for the analyses. Precipitation-quality data from the National Atmospheric Deposition Program (NADP) and bottom-material-quality data from the National Uranium Resource Evaluation (NURE) were used to supplement the water-quality data from NWIS. Concentrations of nutrients were available from 3 precipitation sites established for longterm monitoring purposes, 883 wells (854 synoptic areal survey sites and 29 project and research sites), 23 springs (17 synoptic areal survey sites and 6 project and research sites), and 894 bottom-material sites (840 synoptic areal survey sites and 54 project and research sites). Concentrations of nutrients and (or) suspended sediment were available from 128 streams (36 long-term monitoring sites, 51 synoptic areal survey sites, and 41 project and research sites). Concentrations of nutrients and suspended sediment in streams varied temporally and spatially and were related to land use, agricultural practices, and streamflow. A general north-to-south pattern of increasing median nitrate concentrations, from 2 to 5 mg/L, was detected in samples collected in study unit streams. In streams that drain areas dominated by agriculture, concentrations of nutrients and suspended sediment tend to be elevated with respect to those found in areas of other land-use types and are related to the amount of commercial fertilizer and animal manure applied to the area drained by the streams. Animal manure is the dominant source of nitrogen for the streams in the lower, agricultural part of the basin. Concentrations of nutrients in samples from wells varied with season and well depth and were related to hydrogeologic setting. Median concentrations of nitrate were 2.5 and 3.5 mg/L for wells drawing water at depths of 0 to 100 ft and 101 to 200 ft, respectively. The lowest median concentrations for nitrate in ground water from wells were generally found in siliciclastic-bedrock, forested settings of the Ridge and Valley Physiographic Province, and the highest were found in carbonate-bedrock agricultural settings of the Piedmont Physiographic Province. Twenty-five percent of the measurements from wells in carbonate rocks in the Piedmont Physiographic Province exceeded the Pennsylvania drinking-water standard. An estimate of mass balance of nutrient loads within the Lower Susquehanna River Basin was produced by combining the available information on stream loads, atmosphericdeposition loads, commercial-fertilizer applications, animal-manure production, privateseptic-system nonpoint-source loads, and municipal and industrial point-source loads. The percentage of the average annual nitrate load carried in base flow of streams in the study unit ranged from 45 to 76 percent, and the average annual phosphorus load carried in base flow ranged from 20 to 33 percent. Average annual yields of nutrients and suspended sediment from tributary basins are directly related to percentage of drainage area in agriculture and inversely to drainage area. Information required to compute loads of nitrogen and phosphorus were available for all sources except atmospheric deposition, for which only nitrogen data were available. Atmospheric deposition is the dominant source of nitrogen for the mostly forested basins draining the upper half of the study unit. The estimate of total annual nitrogen load to the study unit from precipitation is 98.8 million pounds. Nonpoint and point sources of nutrients were estimated. Nonpoint and point sources combined, including atmospheric deposition, provide a potential annual load of 390 million pounds of nitrogen and 79.5 million pounds of phosphorus. The range of percentages of the estimated nonpoint and point sources that were measured in the stream was 20 to 47 percent for nitrogen and 6 to 14 percent for phosphorus. On the average, the Susquehanna River discharges 141,000 pounds of nitrogen and 7,920 pounds of phosphorus to the Lower Susquehanna River reservoir system each year. About 98 percent of the nitrogen and 60 percent of the phosphorus passes through the reservoir system. Interpretations of available water-quality data and conclusions about the water quality of the Lower Susquehanna River Basin were limited by the scarcity of certain types of water-quality data and current ancillary data. A more complete assessment of the water quality of the basin with respect to nutrients and suspended sediment would be enhanced by the availability of additional data for multiple samples over time from all water environments; samples from streams in the northern and western part of the basin; samples from streams and springs throughout the basin during high base-flow or stormflow conditions; and information on current land-use, and nutrient loading from all types of land-use settings.

Maryland, Pennsylvania↗
USGS1996

Occurrence and concentrations of volatile organic compounds in shallow ground water in the Lower Susquehanna River Basin, Pennsylvania and Maryland

This report presents the results of a regional assessment of volatile organic compounds (VOC's) in ground water from six sampling areas within the Lower Susquehanna River Basin. The sampling areas, selected to represent aquifers where ground water is used as a drinking water supply, include four areas underlain by limestone, one area underlain by crystalline bedrock, and one area underlain by interbedded sandstone and shale. The land use is rural in five areas and urban in one area. Samples were collected in 1993-95 from 118 wells ranging from 30 to 226 feet deep. Analyses for 60 VOC's at detection levels ranging from 0.05 to 0.2 mg/L (micrograms per liter) reveal the presence of 24 compounds. The compounds were present in water from 32 of the 118 wells. Methyl tert-butyl ether was the most commonly detected compound. Concentrations of methyl tert-butyl ether, found in 16 of the 118 wells, ranged from 0.11 to 51 mg/L. Chloroform was the second most commonly detected compound. The highest concentration detected in a water sample was 61 mg/L of chloroform. None of the detections in samples from wells used as drinking water supplies exceeded the Maximum Contaminant Levels or Lifetime Health Advisory Levels established by the U.S. Environmental Protection Agency. However, the 51 mg/L of methyl tert-butyl ether, detected in water from a monitoring well, is in the 20 to 200 mg/L range proposed for a Lifetime Health Advisory Level. The occurrence of VOC's in limestone aquifers in the Great Valley near Harrisburg, Pa., is influenced by land use. VOC's occur more frequently in the urban area than in the agricultural area. Within the urban area, analyses of samples from wells, springs, and a spring-fed stream show contaminated ground water discharging from springs and flowing into the stream.

Maryland, Pennsylvania↗
USGS1990

Effects of tillage practices and carbofuran exposure on small mammals

We compared population estimates, body mass, movement, and blood chemistry of small mammals between conventionally tilled and no-till cornfields in Maryland and Pennsylvania to evaluate the effects of tillage practices and carbofuran exposure on small mammals. Estimates suggest that populations of white-footed mice ( Peromyscus leucopus ) were not significantly related (P > 0.05) to tillage practice or to the presence of winter rye cover crops. Late summer differences in animal mass and movement, and in the proportion of reproductively inactive animals imply that characteristics of individuals and reproductive activity can be affected by tillage practices and winter cover crops. The presence of granular carbofuran had no apparent effect on populations, body mass, or movement in conventionally tilled or no-till fields. Similarly, neither red blood cell acetylcholinesterase, hematocrit, nor liver function were affected by carbofuran use.

Maryland, Pennsylvania↗
USGS1974

Hydrogeology of Antietam Creek basin

The Antictam Creek basin in the Great Valley of Maryland and Pennsylvania is underlain almost entirely by intensely folded and faulted lower Paleozoic carbonate rocks. The ground-water discharge of the basin is about 85 percent of the total discharge, in contrast with less than 70 percent of the total discharge in two small basins underlain by igneous and mctamorphic rocks in the Maryland Piedmont. Large quantities of ground water are stored in a thick residual mantle, which overlies the carbonate rocks in the valley and adjacent rnetamorphic rocks in mountain areas on the east edge of the basin. Streams that flow off the mountain areas are major sources of recharge to the carbonate-rock aquifers. Several streams lose a large part of their flow within a mile after reaching the carbonate rocks in the valley, and a few flow directly into swallow holes (sinkholes). The low density of perennial streams in the basin is a result of subsurface drainage through solution cavities along joints, faults, and bedding in the carbonate rocks. The major orientations of straight stream reaches along Antietam Creek and the strikes of major joint sets in quarries are nearly coincident, suggesting that the stream network throughout the basin is joint controlled.

Maryland, Pennsylvania↗
USGS1967

Relative toxicity of lead and selected substitute shot types to game farm mallards

The acute toxicity of lead, three types of plastic-coated lead, two lead-magnesium alloys, iron, copper, zinc-coated iron, and molybdenum-coated iron shot were tested in year-old male game farm mallards. Mallards ( Anus platyrhynchos ) were fed eight number 6 shot of each type and observed for a period of 60 days. Ducks used totaled 230 and most shot types were tested in three replicates of 8 ducks each. Mortality and losses of body weight were the criteria used for judging toxicity. Three types of plastic-coated lead shot were as toxic (93 percent) as the commercial lead shot (96 percent). The average mortality in mallards fed lead-magnesium alloy shot was less (58 percent) than that occurring in birds fed commercial lead shot. Mortality among mallards fed iron, copper, zinc-coated iron or molybdenum-coated iron shot was significantly less than in birds fed lead shot, and was not significantly greater than the conrtols.

Maryland, Pennsylvania↗