Geology topics

Michael J. Langland

Publications and source records attributed to Michael J. Langland.

25 records · Page 2Linked to original sources

USGS2002

The U.S. Geological Survey and the Chesapeake Bay – The role of science in environmental restoration

The Chesapeake Bay is the Nation's largest estuary and historically supported one of the most productive fisheries in the world. In addition to supporting aquatic communities and wildlife, the bay's watershed serves the economic and recreational needs of 15 million people. The fertile soils of the watershed support significant agricultural production. Unfortunately, the commercial, economic, and recreational value of the bay and its watershed has been degraded by poor water quality, loss of habitat, and overharvesting of living resources. Since the early 1980's, the Chesapeake Bay Program, which is a partnership among Maryland, Virginia, Pennsylvania, the District of Columbia, the Federal Government, and the Chesapeake Bay Commission, has been formulating and implementing restoration goals to restore living resources, minimize habitat loss, and reduce the amount of nutrients, sediment, and toxic substances entering the bay. The U.S. Geological Survey has the critical role of providing unbiased scientific information to be used in helping to formulate, implement, and assess the effectiveness of restoration goals in the bay and its watershed.

Chesapeake Bay watershed↗

USGS2000

Trends and status of flow, nutrients, and sediments for selected nontidal sites in the Chesapeake Bay Watershed, 1985-98

Data from 30 stream sites in nontidal portions of the Chesapeake Bay Watershed were analyzed to document annual nutrient and sediment loads and trends for the period 1985 through 1998 as part of an annual water-quality update for the Chesapeake Bay Program. Annual loads were estimated by use of the U.S. Geological Survey ESTIMATOR model and are available upon request. Trends were estimated by use of either linear regression, Seasonal Kendall, or Kendall-Theil tests. Trends were reported for monthly-mean flow, monthly load, flow-adjusted concentration, and flow-weighted concentration. Mean yields and median concentrations were calculated to help assess current water-quality status and to facilitate comparisons between basins. The trend in flow was upward at 12 of the 30 sites. Trends of nutrient and sediment load were upward at these same 12 sites. Trends in flow-adjusted and flow-weighted concentrations varied by species. Trends in flow-weighted concentrations were generally upward or not significant for the nitrogen species and parallel or not significant for phosphorus species. Trends in flow-adjusted concentrations were downward at nearly all sites for sediment and dissolved solids in the Susquehanna and Potomac River Basins and generally were not significant in the Virginia river basins.

Delaware;Maryl;New York;Pennsylvania;Virginia;West↗

USGS1998

Changes in sediment and nutrient storage in three reservoirs in the lower Susquehanna River Basin and implications for the Chesapeake Bay

The Susquehanna River contributes nearly 50 percent of the freshwater discharge to the Chesapeake Bay in a year of normal or average streamflow. The river also transports the greatest amount of nutrients (estimates of nearly 66 percent of the nitrogen and 40 percent of the phosphorus load) from all nontidal areas in the Chesapeake Bay Basin. Excessive nutrients in the Bay result in algal blooms that decrease the amount of light reaching submerged aquatic vegetation, and upon decomposition, deplete the oxygen in the water. In a normal-flow year, the Susquehanna River also contributes about 25 percent of the sediment load from non-tidal areas to the Bay. Suspended sediments also reduce light needed by submerged aquatic vegetation and can smother living-resource habitat and obstruct fish gills. A reservoir system consisting of Lake Clarke, Lake Aldred, and Conowingo Reservoir is formed by three consecutive hydroelectric dams on the Lower Susquehanna River. Safe Harbor Dam, which forms Lake Clarke, was built in 1931. Holtwood Dam, the smallest of the three, was built in 1910 to form Lake Aldred. The largest and most downstream dam, Conowingo Dam, was built in 1928 and forms Conowingo Reservoir. Since construction, the reservoirs have been filling with sediment and sediment-associated nutrients. The upper two reservoirs have reached their capacity to store sediments and generally no longer trap nutrients and sediments. Conowingo Reservoir has not reached storage capacity, however, and is currently trapping about 70 percent of the suspended-sediment load, 2 percent of the total-nitrogen load, and 40 percent of the total-phosphorus load that would otherwise be discharged to the Chesapeake Bay (Ott and others, 1991). In 1990, 1993, and 1996, the U.S. Geological Survey collected information on the depth to sediment in the reservoirs to determine the remaining sediment-storage capacity in the reservoir system and to estimate when the reservoirs will reach sediment-storage capacity. In addition, sediment cores were collected and analyzed in 1993 and 1996 to determine the nutrient mass remaining in the Conowingo Reservoir. The 1996 data collection followed a major flood in the Susquehanna River Basin.

Fact Sheet↗

USGS1998

Status yields and trends of nutrients and sediment and methods of analysis for nontidal data-collection programs, Chesapeake Bay basin, 1985-96

Data from more than 200 sites in nontidal portions of the Chesapeake Bay were compiled to document annual nutrient and sediment loads and trends for the period 1985 through 1996 as part of the 1997 Reevaluation of the Chesapeake Bay Program goal of reducing nutrient loads 40 percent by the year 2000. Annual loads were estimated by use of the Minimum Variance Unbiased Estimator (MVUE) model at 95 sites with continuous streamflow data. Trends were estimated by use of either the MVUE or the Seasonal Kendall test at 202 sites and are presented in tables in this report. Trends analyzed in nutrient and sediment concentrations were reported as non-streamflow adjusted and streamflow adjusted if possible. Mean yields from the MVUE model and median concentrations from the Seasonal Kendall test were calculated to help facilitate comparisons between basins.

Open-File Report↗

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↗

USGS1996

Quality of ground water at selected sites in the upper Mahoning Creek Basin, Pennsylvania

The ground-water quality of the upper Mahoning Creek Basin is largely unknown. Human activities in the basin have altered much of the landscape. The presence of coal mining, oil and gas exploration, agriculture, on-lot septic systems, and commercial development within the basin can introduce contaminants altering the natural chemistry of the ground water. Data collected to document current ground-water quality also can serve as a baseline for comparison of any future water-quality changes by continuing human activities. This report presents the results of a synoptic ground-water-quality sampling in the upper Mahoning Creek Basin. Present ground-water quality in the basin is characterized in relation to published standards, local land-use activities, and other areas with similar natural characteristics.

Fact Sheet↗

USGS1995

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

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 of 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 nutrient-management 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 from 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. Eighty-four 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.

Pennsylvania↗