Receiving water standards are based on what criteria?

Receiving water standards are primarily based on the tolerance of the stream to pollutants. This approach takes into account the natural characteristics and ecological health of the water body, including how it can absorb and mitigate the impacts of contaminants. Tolerance levels are determined through scientific studies that assess how various pollutants affect aquatic life, water quality, and the surrounding ecosystem. Establishing standards based on these tolerance levels helps to protect aquatic habitats and ensure that water bodies remain safe for recreational use and support a diversity of life.

In contrast, economic factors primarily deal with the costs and resources available for compliance but do not directly influence the ecological health criteria of the receiving water. Land use policies could shape how water is managed but are not intrinsic to the scientific evaluation of the water's ability to handle pollutants. Water temperature variations can influence the types of organisms present and their tolerance to pollutants, but they are not the foundational criteria for setting receiving water standards. Thus, the focus on the tolerance of streams to pollutants ensures that water quality standards relate directly to the environmental and biological integrity of the ecosystems they support.