Total Dissolved Solids in Monongahela River Drop Significantly Below State, Federal Limits:
DEP to Continue Monitoring Levels, Taking Samples

PA DEP News Release
21 January 2009

Dept. of Environmental Protection
Southwest Regional Office
400 Waterfront Drive
Pittsburgh, PA 15202
Helen Humphreys
Phone: (412) 442-4183

PITTSBURGH - The Department of Environmental Protection confirmed today that levels of total dissolved solids, or TDS, in the Monongahela River have dropped and remain well below state and federal guidelines. Three weeks of laboratory data on water samples from the river found TDS levels below the 500 parts per million criteria established by the department and the U.S. Environmental Protection Agency. The latest results from Dec. 30 recorded levels ranging from 110 ppm to 196 ppm.

In comparison, lab results for water samples collected on Oct. 22, when the highest TDS levels were detected, ranged from 438 ppm to 908 ppm.

Unusually high TDS levels were first detected on Oct. 11 at points along approximately 70 stream miles on the Monongahela River between the West Virginia border and the confluence of the Youghiogheny and the Monongahela rivers in McKeesport, Allegheny County.

By November, high TDS levels were detected as far north as "The Point" in Pittsburgh, where the Monongahela meets the Allegheny River to form the Ohio River.

DEP will continue to monitor the United States Geological Survey river gauges for conductivity, which is a far less expensive and time consuming alternative to lab analyses. If conductivity levels increase significantly, DEP may resume sampling.

In addition, DEP is working with water suppliers through the River Alert and Information Network to develop a regional water quality monitoring system.

While elevated levels of TDS do not represent a major human health risk, TDS can affect the taste and odor of drinking water. For that reason, secondary maximum contaminant levels of 500 parts per million were established for the commonwealth's drinking water and waterways.

TDS is a measure of all elements dissolved in water and can include carbonates, chlorides, sulfates, nitrates, sodium, potassium, calcium and magnesium. Sources of TDS can include abandoned mine drainage, stormwater runoff, waste water from gas well drilling and discharges from industrial or sewage treatment plants.

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