1 Numeric Nutrient Criteria Development Strategies for R.I. Estuarine Waters

This document is provided to the RIDEM OWR to lay out a conceptual approach to developing numerical nutrient criteria for marine waters of the state. As the State agency responsible for administering water quality standards and criteria, the Rhode Island Department of Environmental Management (RIDEM) previously committed to developing refined nutrient criteria to strengthen protection of Rhode Island’s surface waters. The negative effects of excessive loadings of nutrients to both fresh and estuarine waters constitute a well recognized water quality concern in the State. Over the last decade, a range of actions have been taken to better control and mitigate nutrient pollution. Refining water quality standards through the adoption of numeric nutrient criteria is intended to strengthen the basis for future mitigation and management of nutrient water pollution including allocation of acceptable pollutant loadings as determined in new total maximum daily load (TMDL) studies. Point Sources In its current water quality regulations, RIDEM has specified a numeric limit for total phosphorus (TP) in freshwater lakes and ponds, and rivers at the point they enter lakes and ponds, but otherwise relied on narrative criteria to support management decision-making. It is important to note that while th