The Pinch of Salt: Monitoring Analysis and Winter Maintenance Strategies within the Long Creek Watershed

In 2009 the United States Environmental Protection Agency exercised its Residual Designation Authority (RDA) in the Long Creek Watershed, a commercial/retail district in the Greater Portland, Maine area. The RDA provision requires stormwater permitting for any landowner with one or more acres of impervious cover including municipalities, state departments of transportation and private and public landowners. This precedent setting use of RDA has led to the establishment of the Long Creek Watershed Management District, which implements the permit requirements for 70% of the watershed's impervious area. Long Creek is the most studied urban watershed in Maine. Its unique regulatory situation allows Long Creek Watershed Management District to evaluate water quality solutions based on site-specific data and implement nontraditional approaches to water quality improvement as it sees fit. The Long Creek Watershed can therefore serve as a model for those entities who wish to proactively manage chloride impacts in their own watershed using data-driven policy changes that might include minimizing plowed parking spaces and educating plowing contractors on proper salt application methods. The Long Creek Model has demonstrated that businesses, nonprofit organizations, and regulatory entities can work together to implement a watershed management plan. Under the right geochemical conditions, continuous specific conductance data coupled with periodic chloride grab sampling can provide a regression model to calculate estimated continuous chloride concentrations in the stream. The regression identifies temporal and spatial concentration variability, and, when coupled with stream stage and precipitation data, can reveal any significant sources of chloride during baseflow conditions.