Managing expectations: Creating a community based stormwater pond nutrient management progra

Degradation of surface waters is a critical concern in the state of Florida. Regulatory frameworks and best management practices (BMPs) exist to protect the designated uses of natural surface waters and reduce the impact of runoff from upstream activity. Stormwater ponds (SWPs) are an increasingly popular BMP in residential developments and are assumed to remove at least 80% of the nutrient load from the contributing watershed to meet regulatory requirements. Residential SWPs also generate a property value premium by creating "waterfront" property with social expectations related to aesthetics and recreational value. The management of SWPs to meet social expectations often includes the removal of biological responses to increased nutrient concentrations, resulting in a reduction of the nutrient removal efficiencies and failure to meet regulatory requirements. In this study, a method was developed to quantify social expectations of SWPs and define numeric nutrient criteria required to meet social demands and regulatory criteria. Nutrient and chlorophyll-a water column concentrations in SWPs within a southwest Florida community were sampled and significant nutrient-response relationships were established for clear and colored systems. The SWP nutrient-response relationships were compared to those established for Florida's numeric nutrient criteria for natural lakes and found to be weaker but significantly different. To quantify social expectation criteria, a web-based survey was created to identify thresholds of impairment based on water column chlorophyll-a concentrations. Results indicated mean community-based thresholds range from 20-30 microg˙l-1. Preferred thresholds were found to increase with frequency of use for recreational activities and respondents who correctly identified the role of algae in SWPs had significantly greater thresholds than those who did not. Age, seasonality of residence, sex and presence of children in the household were also found to have a significant impact on preferred thresholds. Based on the identified community-based thresholds and nutrient-response relationships, SWP numeric nutrient criteria were established and the potential impacts were estimated. The findings and methods identified in this study indicate the significant potential to effectively meet regulatory requirements and social expectations of SWPs, improving management practices and reducing downstream impacts of runoff from residential development.