Public Comment -- April 2, 2004
The USGS studies (2, 3) utilized newly developed laboratory methods at its Denver laboratories to provide baseline information on the environmental occurrence of a wide range of organic wastewater contaminants in surface water used or having the potential to be used as sources of drinking water. Analytical methods were developed for the determination of more than 100 contaminants typically found in domestic, industrial, and agricultural wastewaters. Examples of these unregulated contaminants include pharmaceuticals. antibiotics, hormones, personal care product ingredients, and various industrial and commercial products. Thirty stream sampling locations were selected in New Jersey, mostly located downstream or near potential sources of human wastewaters. The strategic field sampling plan for this project involved a vulnerability assessment that
utilized the basin hydrodynamics, land use coverage, and percent wastewater contribution to stream flow as elements. Some locations had no wastewater discharges upstream, and the maximum number of such discharges upstream from a sampling location was 51. Over 90 percent of the stream water samples contained detectable concentrations of one or more of the target compounds. The number of compounds detected per sample ranged from zero to 32, with a median of 11. The total number and concentration of target compounds detected per sample correlates significantly with the percentage of streamflow contributed by sewage treatment plants, indicating that the likely priman-source for many of these compounds is effluent from the wastewater treatment process.
In addition, 24 water samples were collected at selected locations throughout a water-treatment facility and from the two streams that serve the facility. Several compounds frequently detected in raw-water supplies were also frequently detected in samples of finished water including prescription and non-prescription pharmaceuticals and their metabolites, fragrance compounds, flame retardants and plasticizers, cosmetic compounds, and a solvent.
Results from these studies indicate that organic contaminants that represent a broad suite of uses and origins can enter and persist in environmental waters and subsequently occur in finished drinking water supplies. Also, the studies indicate that unregulated contaminants tend to occur at those surface water systems where the percentage of streamflow contributed by sewage treatment plants is high. That is, the highest numbers (and highest concentrations) of wastewater contaminants occurred in surface water intakes that were downstream of a wastewater discharger. In most instances, the water systems did not have air-stripping present. This is not surprising, as volatile contaminants are often reduced to below detectable levels from the water before they can reach the intakes. On the other hand, the semi- and non-volatiles are able to remain in the water phase and reach the intake.
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