The Use of A Prioritization Index to Rank Mine Discharges and Tributary Streams for Remediation Consideration

Abstract

The Pittsburgh, Pennsylvania, project office of the U.S. Geological Survey (USGS) has been involved in various studies of the effects of mine drainage on stream water quality. Two of these studies focused on prioritizing the severity of mine discharges and the relative impairment of streams. One study located and sampled abandoned coal-mine discharges in the Stonycreek River Basin in Pennsylvania and prioritized the mine discharges for remediation. This priority ranking system, or prioritization index (PI) developed for mine discharges, also was used to prioritize tributary streams and reaches of the mainstem throughout the lower Cheat River Basin in northern West Virginia. The major difference between the PIs of the studies was that the Stonycreek River Basin index was applied to chemical loadings of point-source mine discharges, whereas the Cheat River Basin index was applied to mainstem river sites, tributary stream sites, and subbasin stream sites within the major tributaries in terms of chemical yields. The PIs for both studies were based on a site-to-site water-quality comparison of the loads and yields of selected chemical constituents that included total iron, total manganese, dissolved aluminum, total heated acidity, and dissolved sulfate. Water discharge was an important physical measurement used to calculate the loads and yields of the chemical constituents. Water discharge and pH were used as "tiebreakers" in developing the PI. All of these factors are related either directly or indirectly to the effects of coal-mine drainage on water quality. A computerized spreadsheet of the water-quality data was used to simplify the PI calculations. The PI, developed to assist water- resource managers in considering remediation possibilities at specific mine discharges in the Stonycreek River Basin or in the many tributary basins and subbasins throughout the lower Cheat River Basin, is suitable for application in other watersheds affected by mine drainage. Some potential modifications to improve the index method are discussed.