Grawemeyer Colloquium Papers


Across the world, it is estimated that 4.5 billion people live near water sources “impaired” for use or contact. Standards for human-interaction are established by international organizations such as the WHO, and legislative bodies from national to local levels with jurisdiction over the quality of our waterways to ensure public & environmental health. Standards are often assessed from “grab-samples” taken from a waterbody at a certain time, with a minimum number analyzed. Water-quality standards in the United States are enforced under the Clean Water Act (CWA) via the Environmental Protection Agency (EPA), applying to “waters of the United States” (WOTUS). After January 2019, “WOTUS” has been interpreted with variation as “traditionally navigable waters”, their tributaries, or bodies with a “significant nexus” to them – leaving others outside federal jurisdiction or protection. However, since the CWA requires States to develop “Total Maximum Daily Loads” to provide a framework for when water quality is not healthy for contact, States enforce TMDL-standards under their own jurisdictions. Regardless of whether one could traditionally “mark twain” to navigate a vessel on a stream, or the variations in State jurisdictions, the most legally promoted scientific methodology used to assess TMDL’s for surface water quality across the U.S. has not changed: grab-sampling.

This paper describes a water quality study focused in southwest Louisville, Kentucky, compared to two different streams in the Salt River sub-basin to the Ohio River. The study developed cumulative methods for sampling that were accessibly cost-effective. The method profiled fecal contamination before stream-restoration with strong correlations compared to frequent grab-samples, diagnosed contamination causes, and ultimately, suggests improvement over TMDL grab-sampling and a need to form new standards with cumulative methods.