Water Quality: Steps for Understanding and Implementing an NPDES Monitoring Program

NPDES permits are intended to protect or restore the physical, chemical, and biological integrity of waters of the United States. This is done by establishing standards for a variety of pollutants that are protective of a streams designated beneficial use. Water quality standards must also support aquatic life uses and habitat protection. Once established, water quality limits must be measured at a frequency and using a methodology approved by the permit and regulatory agency with oversight.
Sample collection techniques can include grab samples, flow-weighted composite samples, and time-weighted composite samples. Sample collection containers must be “laboratory cleaned”, as well as of the proper material (i.e., glass, amber, plastic, etc.), and contain the right preservative(s). Samples must be maintained under “chain of custody” and then be analyzed by an accredited laboratory. Laboratory accreditation is given based on approved method, and is not a blanket assertion the any lab can run any test method.
Results returned from the laboratory must be reviewed against the relevant standards to determine whether a discharge is in compliance with environmental criteria, or not. A determination of non-compliance is likely to require notification reporting to the regulatory agency, and maybe others, including a City, County, Department of Transportation, or other entity with oversight of the discharge location.
How does a permittee set up a successful monitoring program? What records should be maintained to demonstrate that an approved methodology was used at each step along the monitoring process? Can effluent limitations be predicted and where should an outfall be located to aide in compliant discharges? What information should be included in a non-compliance notification? This discussion will review water quality metrics, monitoring protocols, typical monitoring events found in NPDES General and Individual permits, and will include a review of non-compliance reporting and responses.