Linking Receiving Water Impacts to Sources and to Water Quality Management Decisions

This report describes one of the efforts undertaken as part of this research challenge. Purpose The purpose of the overall WERF “Linkages” research challenge is to develop a better understanding of the linkages between: Sources of a constituent; The predicted and measured adverse impacts of the constituent on receiving waters; and Controls available to address these adverse impacts and their total costs and benefits. Additionally, it is a goal of this research challenge to identify the knowledge and information gaps that need to be addressed such that a comprehensive and cost effective pollutant control strategy can be developed and implemented for a given set of constituents. 

Linking water quality impacts to the many constituents of concern is a daunting task, and several research efforts are included in this WERF research challenge to adequately address the major constituent categories. The focus of this report is on developing a state of the knowledge approach to establishing the linkages listed above, and to apply this approach to nutrients as a source constituent. Nutrient pollution is one of the leading causes of water quality impairment in the nation, and the quantity of nutrients reaching the nations waters has dramatically escalated over the past 50 years (EPA, 2009). Nitrogen and phosphorus loadings to waterbodies impact water quality by stimulating plant and algae growth which subsequently may result in depletion of dissolved oxygen, degradation of habitat, harmful algal blooms, and impairment of drinking water sources. Effectively controlling nutrient pollutant loadings to receiving waters has thus become a major challenge for resource managers. Recent requirements by EPA for numeric nutrient criteria in Florida have made this an urgent need, especially for nitrogen since it is the limiting nutrient in Florida’s coastal waters. The linkage of Florida receiving water impacts to nitrogen sources will therefore be used as a case study for an initial demonstration of the approach developed in this project. 

Specifically, the scope of this project is to: Develop a technically defensible framework for assessment of the linkage between nitrogen sources and water quality responses; Understand how the source-response linkage is influenced by nitrogen source controls; Develop an approach to evaluate the effectiveness of nitrogen source control strategies; Gather and summarize available information and data relative to the Florida nitrogen situation, and identify any data or knowledge gaps that would need to be filled to implement the recommended approach in Florida.