An Innovative Approach to Identifying Opportunities for Non-Point Source Pollution Control Across Multiple Watersheds

Sanitation District No. 1 of Northern Kentucky (SD1) is a sanitary and storm water utility managing a sewer services area covering more than 200 square miles, across three counties in northern Kentucky. In 2005, SD1 entered into a Consent Decree to address combined sewer overflows (CSOs) and sanitary sewer overflows (SSOs) in its service area. This agreement endorses an innovative watershed-based approach to improving water quality, including the requirement to develop watershed plans for sixteen watersheds and the provision that “If watershed plans identify… nonpoint sources… that are contributing to water quality impairment… the Watershed Plans shall also identify… control measures… to offset the level of CSO controls or to delay the elimination of an SSO… ”. To determine whether opportunities for control measures exist in the watersheds where CSOs and SSOs have been identified, an innovative approach was developed and implemented. The approach developed for SD1 uses a geographic information system (GIS) spatial analysis, with existing spatial data, to identify control measure opportunities. This paper describes the process, discusses its applicability and scalability to other watersheds, and uses the SD1 experience as a case study of its application.