The Watershed Resources Registry is a new interactive online mapping tool, created by federal, state, and local partners. The tool prioritizes areas for preservation and restoration practices in different landscapes across an entire state by using a variety of absolute and relative criteria to rank areas from 1- (least) to 5-stars (most suitable). The State of Delaware launched its Watershed Resources Registry in 2016. Potential applications of the Watershed Resources Registry are promising; however, few studies have been completed to assess the validity of the Watershed Resources Registry in Delaware.
The Municipal Separate Storm Sewer System Permit Program, under the United States Environmental Protection Agency’s Clean Water Act, requires New Castle County, Delaware Department of Transportation, and other permittees to develop Water Quality Improvement Plans for two watersheds over the next year. The purpose of this research is to determine if the Watershed Resources Registry is suitable to predict sites for water quality improvement projects. If the Watershed Resources Registry is a suitable predictive tool it can be used to develop Water Quality Improvement Plans for New Castle County and Delaware Department of Transportation. To determine suitability: a relationship was examined between Watershed Resources Registry ranks and pre-treated pollutant loads and then a spatial resolution threshold was defined for the Watershed Resources Registry’s site selection. This study used a completed Water Quality Improvement Plan for the Christina River Watershed that provided 26 proposed best management practice sites. The Watershed Resources Registry ranks were obtained from the stormwater compromised infrastructure restoration layer and pre-treated pollutant loads of total nitrogen, total phosphorus, and total suspended solids in pounds per acre per year were calculated by the Delaware Urban Runoff Management Model. Geographic information systems were used to map and interpret data.
This study concluded three key results. One, the Delaware Urban Runoff Management Model is a model that can be used in tandem with the Watershed Resources Registry. The Watershed Resources Registry now offers a new perspective when using the Delaware Urban Runoff Management Model because loads can be associated with Watershed Resources Registry ranks in different watersheds. Two, the higher Watershed Resources Registry ranks associated with higher pollutant loads on a larger scale. Three, the Watershed Resources Registry is best suited for at least a 4-acre resolution. This resolution provides “hot spot” areas to focus on, rather than specific site locations, therefore it should only be used for a screening tool. The Watershed Resources Registry has potential to be widely used as a screening tool to locate stormwater restoration practices throughout the Mid-Atlantic states.
Analysis of the Watershed Resources Registry Using GIS to Evaluate Stormwater Restoration Practices in the Christina River Watershed (2019)
Jillian S. Young