Pennsylvania Water Science Center



Chuck Cravotta


Allegheny-Monongahela National Water-Quality Assessment (NAWQA)

This study ended in 2000.


A consistent description of the Nation's water resources, that assesses regional and local factors affecting water-quality conditions and trends is needed by policy makers and managers. In the Allegheny-Monongahela River Basin, which includes the headwaters of the Ohio River Basin in western Pennsylvania (figure 1), the quality of many river reaches, tributaries, and ground-water supplies is degraded by acidic mine drainage (AMD), oil- and gas-well discharges, combined stormwater-sewer overflows, sediment loading, agricultural runoff, and urban-industrial discharges. AMD from abandoned bituminous coal mines is the most extensive cause of degraded surface-water and ground-water quality.

Map of the Allegheny-Monongahela NAWQA study unit

Figure 1.--Map of the Allegheny-Monongahela NAWQA study unit


Funding was provided by the USGS-Water Resources Division (WRD) Federal Program during 1994-2000. The USGS-WRD communicated and coordinated activities through a local liaison committee consisting of interested scientists and water-resources managers from Federal, State, and local agencies and universities.


Several reports were produced during the study (SIR is Scientific Investigations Report, WRIR is Water Resources Investigations Report and C is USGS Circular report);

SIR 2006-5059. Ground-Water Quality in Unmined Areas and Near Reclaimed Surface Coal Mines in the Northern and Central Appalachian Coal Regions, Pennsylvania and West Virginia, by Steven D. McAuley and Mark D. Kozar

WRIR 98-4258. Stream water quality in coal mined areas of the Lower Cheat River Basin, West Virginia and Pennsylvania , during low-flow conditions, July 1997, by D.R. Williams, M.E. Clark, and J.B. Brown

WRIR 99-4208. Effects of coal-mine drainage on stream water quality in the Allegheny and Monongahela River River Basins—Sulfate transport and trends, by J.I. Sams , III and K.M. Beer.

WRIR 00–4061. Nutrients and Organic Compounds in Deer Creek and South Branch Plum Creek in Southwestern Pennsylvania , April 1996 through September 1998 by Donald R. Williams and Mary E. Clark

C-1202. Water quality in the Allegheny and Monongahela River Basins , Pennsylvania , West Virginia , New York , and Maryland , 1996-98, by R.M. Anderson, K.M. Beer, T.F. Buckwalter , M.E. Clark , S.D. McAuley , J.I. Sams , III, and D.R. Williams. 2000.

A web site for the Allegheny-Monongahela River Basin NAWQA study is also available.


In 1994, NAWQA activities began in the Allegheny-Monongahela River Basin. An intensive data collection effort was carried out during 1994-1998. Water quality and aquatic biology were collected at 10 fixed-network stream sites. The 10 sites have been selected for sampling either to represent basins dominated by a particular land use, such as coal mining, urban residential, agricultural, or forest or to represent basins having an integration of several land uses.

Surface water was sampled monthly or more frequently (at several high flows) at the 10 fixed network sites to evaluate seasonal conditions and trends in water quality. Constituents analyzed included common ions, iron, manganese, aluminum, nutrients, dissolved organic carbon, pH, dissolved oxygen, specific conductance, and temperature. At some sites, specific conductance and temperature were monitored continuously. For selected samples, pesticides, volatile organic compounds, and trace elements were analyzed. In addition to water-quality samples, data for habitat, algae, macroinvertebrates, fish community, fish tissue, and bed sediment were collected one or more times at the 10 fixed sites. Fish tissue and bed sediment have been sampled for hydrophobic organic compounds and trace elements from an expanded network consisting of the 10 fixed sites plus 9 other sites located below urban land use or coal mining land use to describe the occurrence of these constituents in the study area.

Three basins were selected for inclusion in the sampling network because of mining effects. The Stonycreek River Basin, the Dunkard Creek Basin, and the lower reaches of the Cheat River Basin, which is an integrator of several land uses, are dominated by coal mining effects. Samples for trace elements in dissolved and suspended forms in high, medium, and low flows have been collected at these sites. During 1997, in cooperation with the WVDEP, more than 100 stream sites in the lower Cheat River Basin were sampled in a synoptic effort to characterize surface-water quality in coal mining areas containing many abandoned mine discharges. (See WRIR 98-4358)

In 1998, 120 sites throughout the Allegheny-Monongahela River Basin study area and 60 sites in the adjacent Kanawha-New River NAWQA study area were sampled . These sites were sampled 20 years ago as part of the National Coal Hydrology Program conducted by the USGS in cooperation with the Office of Surface Mining and Reclamation to inventory the extent of water-quality degradation in coal- mining areas. The NAWQA synoptic sites were selected for sampling based on predominance of particular types of coal mining (such as surface mining or underground mining) or particular ages of coal mining operations (before or after implementation of the 1977 Surface Mining Control and Reclamation Act) in the basin above the sample site. Basins without any known coal mining were also sampled to serve as reference basins. The sampling effort provided a regional examination of the status and trends of water quality improvement and to examine the relations between coal mining operations and water quality. In addition to water column parameters that include pH, acidity, Fe, Mn , Al, and flow, benthic organisms, habitat, and trace-element composition of bed sediment were sampled at selected sites .

Ground water in fractured coal-bearing rocks of the Appalachian Plateau and in unconsolidated sediments of the valley-fill deposits in the northern parts of the study area, were sampled at 30 sites as a reconnaissance effort to evaluate general water- quality conditions. In addition to constituents listed for the surface-water sites, water from wells also was sampled for trace elements (in the fractured rocks) and radon. In 1997-98, ground water was sampled from 30 wells located near reclaimed surface mines to evaluate effects on ground-water quality that may exist after nearby reclamation efforts conclude. In addition, ground water from 5 or more wells located in unmined areas will be sampled to provide reference conditions.

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