Charlestown's EPA Southeast New England Program (SNEP) Grant

Charlestown's EPA SNEP Grant Program - The Charlestown Coastal Watershed Protection and Restoration Program

Final Technical Report - Submitted March 24, 2021


The Town of Charlestown, Rhode Island applied for and successfully received funding in 2016 from the United States Environmental Protection Agency (US EPA) Southeast New England Program (SNEP) for Coastal Watershed Restoration. The Town was uniquely positioned to respond to the initial request for proposals. Over the past 15 years, we have studied extensively the impacts of nutrient loading to our coastal watershed and implemented numerous Town operated measures to document, quantify, manage, and mitigate those impacts.

As a community, we understand that our local groundwater is not only our sole source of drinking water but also this groundwater outwells into our three critically sensitive coastal ponds carrying with it nutrients associated with the surrounding land uses. Our coastal ponds are the primary economic driver of our local economy, the health of which every Charlestown resident relies on. Our community also only utilizes on-site wastewater treatment system (OWTS) to manage domestic wastewater from every dwelling and business in Town. A community collection system has been determined to be technically and fiscally infeasible and if properly managed OWTS can be an effective means at recycling wastewater. However, the cumulative effect of OWTS in the most densely developed areas of the Town have been identified as the primary source of the nutrient Nitrogen (N) loading to our coastal watershed.

The Town partnered with the University of Rhode Island (URI), Laboratory of Soil Ecology and Microbiology (LSEM) and the New England On-Site Wastewater Training Program (NEOWTP), Save the Bay (STB), and the Salt Ponds Coalition (SPC) for the successful implementation of this project, entitled the Charlestown Coastal Watershed Protection and Restoration Program. The project consisted of three primary tasks.

  • Comprehensive OWTS effluent quality monitoring from existing N-reducing systems to better understand the efficacy of these technologies and establish methods for enhanced management to further mitigate N loading to the Watershed,
  • The replacement of 15 of the most basic substandard OWTS within proximity to one of the most nutrient impacted subwatersheds in the area with the most efficient N reducing OWTS treatment trains available to reduce total N loading to these watersheds, and
  • Stormwater and fertilizer management to focus on non-OWTS related nutrient loading sources to the Watershed through fostering onsite infiltration of stormwater, reduction of fertilizer use and developing citizen scientists to generate interest and involvement in community-based nutrient mitigation of our watersheds.

The project commenced in November 2016 and was finalized on January 1, 2021. Tasks were implemented and completed with overwhelming public support, community engagement and the results exceeded our expectations. This report summarizes in detail all tasks implemented and completed as part of this program, it explains methods, implementation measures, results and findings and implications including plans for continued implementation and describes the feasibility of replicating our tasks outside of our jurisdictional area.


Video Series - Also Available at the Salt Ponds Coalition Video Page

The videos below were also presented as part of a Poster Presentation by the Town at an EPA SNEP symposium entitled "TOMORROW STARTS TODAY: ACTING NOW FOR A RESILIENT SOUTHEAST COASTAL NEW ENGLAND"on October 25, 2019. Click here for the Poster.



The Charlestown Coastal Watershed Protection and Restoration Program includes quarterly sampling of up to 50 Nitrogen reducing septic systems over three years in critical zones within Charlestown's coastal watershed. This information will help to guide and establish a funding program to upgrade 15 substandard or unpermitted older OWTS to N - reducing technology by developing a model to best predict final effluent Nitrogen concentrations, resulting in a reduction of over 150 pounds of nitrogen per year into the Eastern Ninigret Pond/Green Hill Pond Watersheds!

Model development will focus on using a low number of data inputs to ease the transferability and monitoring requirements for other municipalities to adopt the process. Charlestown will also develop a town recommended landscaper process and use it to install 6 demonstration rain gardens on town properties. Two surface water sampling stations in Green Hill Pond to track nutrient impacts will be added to a current monitoring program, as it is the most heavily impacted salt pond in the town.


Project 1 - Nitrogen Reducing OWTS Efficiency Sampling


Researchers from URI LSEM, New England Onsite Wastewater Training Program and the Town have been examining ways to ensure existing Nitrogen reducing septic systems are functioning at the maximum efficiency. It is known that sampling wastewater outflow quality from these types of septic systems is the only way to know if they are meeting the RIDEM established goal for Nitrogen reduction of 19 parts per million. If samples indicate that Nitrogen concentrations are elevated, the systems functions can be modified accordingly using the systems control panel. Even if Nitrogen concentrations are detected above the 19 parts per million threshold, these systems still have been shown to significantly reduce Nitrogen when compared to substandard and conventional systems, typically by greater than 50%.

50 owners of Nitrogen reducing septic systems have volunteered to work with the Town and URI LSEM to have their Nitrogen reducing septic systems sampled quarterly. These data are analyzed for wastewater parameters and compared with occupancy, use, wastewater flow volumes, system age and others. 

Until now, there has been a sampling collection fee and a laboratory fee associated with this type of monitoring and it has not historical been conducted leaving homeowners unaware if their system is meeting the groundwater/drinking water protection requirements. 

Understanding this and using data collected from this EPA SNEP grant and other funding sources, these researchers have identified a low cost sampling tool.  This will save septic system owners $ and assist with groundwater protection. 


Project 2 - Substandard Septic System Replacement with Nitrogen Reducing Technology to Reduce Nitrogen Loading by at least 150 Pounds per Year




Project 3a - Surface Water Quality Sampling in the Densely Developed Watersheds of Charlestown