Ambient Toxicity Monitoring Program

The ambient toxicity monitoring program has proven useful for identifying waterbodies with the potential for aquatic life impairment. Although data for side-by-side lab tests and in situ testing or biosurveys are limited, results indicate that toxicity testing is a reliable indicator of potential aquatic life use impairment.

About one-fourth of the stations sampled on multiple dates have exhibited recurrent lethal or sublethal toxic effects to at least one test species. The frequency of observed toxicity is high, because investigators have generally targeted waterbodies with known or suspected water quality problems.

Waterbodies that have exhibited recurrent toxicity are candidates for more intensive assessments, aimed at confirming the occurrence of toxic conditions or aquatic life use impairment, and determination of sources or causes of toxicity. The Water Quality Protection Division should assume an active role in assisting other agencies with special studies to determine or document the sources of toxicity for waterbodies that have exhibited toxic effects. Effluent and ambient testing may be conducted, using tests employed by the NPDES program, where point sources are suspected as the primary cause of instream toxicity. Toxicity identification evaluations, chemical analyses, and/or biosurveys may be useful for documenting potential causes and effects of observed toxicity.

Response from participating agencies suggests that interest in the program remains high. Requests for increased resources for testing and additional testing capabilities (bulk sediment & marine tests) have been received. Opportunities for acquiring these capabilities should be explored.