Load-Response Models for Establishing Site-Specific Nutrient Goals Based on Water Quality and Biological Response Indicators

This paper summarizes the findings of a research project supported by the Water Environment Research Foundation (WERF) to develop nutrient load-response modeling guidance for water body-specific nutrient goals (e.g., TMDLs, nutrient criteria development, etc.) that covers response indicators, model selection, model development, and model application. Data and research needs to further improve nutrient load-response models are also described. To accompany the modeling guidance, a Nutrient Modeling Toolbox (Toolbox) was also developed from existing and available models. The Nutrient Modeling Toolbox contains 30 process-based, empirical, and hybrid models capable of quantifying the relationship between nutrient loads and their impacts on water quality or ecological response indicators. A Model Selection Decision Tool (MSDT) was developed to filter and select potential models for their specific site, problem, response indicator(s), time and spatial scales. This work provides an alternative to existing U.S. Environmental Protection Agency (USEPA) guidance for setting site-specific nutrient goals, including Numeric Nutrient Criteria.