Concern over water quality impacts from an ever increasing array of potential contaminants has become a major challenge for water resource managers. To better understand the linkages between sources of a constituent, its effect on water quality, and the costs and benefits of controls, the Water Environment Research Foundation (WERF) has undertaken a research challenge entitled “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. 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.

Scope
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.

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