EPA Research Partner Support Story: Assessing the impact of sewering on coastal water quality
Partner: Town of North Kingstown (RI) Departments of Water and Public Works
Challenge: Assessing the impact of sewering on coastal water quality
Resource: Technical support in collaboration with the U.S. Geological Survey (USGS)
Project Period: 2018 – 2024
Many areas rely on septic systems installed at individual homes and businesses to treat most of their wastewater. These systems were designed primarily to remove harmful bacteria, and most allow the bulk of the nutrients, especially nitrogen, in the waste to flow via groundwater into streams, ponds or coastal waters where they can cause problems such as low dissolved oxygen (which can harm fish populations) and nuisance or harmful algae blooms. To solve this problem, many coastal communities are installing sewers to intercept, treat and discharge the waste to less sensitive areas. These projects are expensive for taxpayers and few studies have documented the beneficial effect of sewering on water quality in the receiving waters, which is of interest to communities that invest in them.
“The town of North Kingstown’s main village, Wickford, is a densely settled area on the coast with many houses built between 1780 to 1830. Although direct discharges to the water and most of the cesspool systems have been eliminated, rising sea level and older, inefficient septic systems continue to impact the receiving waters. Sanitary sewers to the business district of the village are being installed. The town needs help persuading residents of the need to extend sewers to the residential areas. The analysis and assessment by the EPA showing improvement of the water quality would really drive the importance of sewers.” – North Kingstown Town Engineer N. Kim Wiegand, PE
Wickford, a small village in North Kingstown, RI, is in the process of installing sewers and hoping to secure and maintain support for their project within the community. EPA ORD researchers have sampled the waters around the town since early 2018, measuring nutrients, dissolved oxygen and several tracers of wastewater and in a collaboration with EPA Region 1 (New England) and USGS starting in 2020, mapping and modeling groundwater and associated nutrient flow into the cove system around Wickford. While it is too early to assess if water quality is improving, EPA ORD and its partners are creating a baseline for comparison after the sewering is finished. EPA ORD is working with the Town of North Kingstown to document the progress of the sewering and remediation of water quality problems in the coves surrounding Wickford (e.g., algae covering cove bottoms and low dissolved oxygen conditions, particularly at night during the summer), and to develop educational materials about the impact of nutrients on coastal waters and the impact of sewering in the coves around Wickford. Eventually the town will use the generated data to determine if sewering has improved local water quality and demonstrate to residents how their investment is paying off in terms of local environmental improvement.