New DEM Stormwater Permit Will Prevent and Reduce Pollution from Runoff in Mashapaug Watershed

Published on Tuesday, April 30, 2024

PROVIDENCE, RI – The Rhode Island Department of Environmental Management (DEM) announced today that it is moving forward with the issuance of a permit to regulate previously unpermitted stormwater discharges into Mashapaug, Spectacle, and Tongue Ponds in the Cities of Cranston and Providence. The DEM permit is a response to petitions filed by Attorney General Peter F. Neronha and the Conservation Law Foundation urging DEM to use provisions of the federal Clean Water Act, which DEM enforces in Rhode Island, to prevent toxic algae blooms, high levels of bacteria, and frequent closures of the ponds in the Mashapaug Watershed.

“DEM is taking this step to clean up an important urban watershed and protect public health by putting property owners on a path and on the clock to reducing pollutant loads,” said DEM Director Terry Gray. “We are confident that that by regulating allowable activities and giving guidance to site owners on how to meet the permit requirements, the problems plaguing the Mashapaug Watershed will be fixed in time. We are grateful for the partnership of Attorney General Neronha and the advocacy of the Conservation Law Foundation in creating the momentum to move forward and tackle this problem.”

“Pollution from stormwater runoff and the issues that flow from it are altogether preventable if we take bold, decisive action,” said Attorney General Peter F. Neronha. “I am grateful to Director Gray and the team at RIDEM for moving forward with establishing a permitting system to address stormwater discharges in the Mashapaug Pond watershed following petitions from our Office and the Conservation Law Foundation, and their commitment to improving the condition of our waterways. These measures, if successfully implemented, will prevent and reduce pollution in these ponds for the benefit of the environmental justice communities where they sit, and potentially serve as a blueprint for future stormwater management efforts in Rhode Island as a whole.”

The Mashapaug Pond Residual Designation Authority permit, which DEM will notice to the public this fall, will include the following requirements:

Permittees — numbering around 70 industrial and commercial properties with an acre or more of impervious cover in the watershed — must develop and implement a site-specific stormwater management plan that describes how they will reduce or eliminate the potential for the discharge of stormwater pollutants.

Permittees must evaluate opportunities to reduce or eliminate impervious (paved and other hard) surfaces and install green infrastructure. (Stormwater runoff is generated from rain and snowmelt that flows over paved surfaces, such as parking lots, carrying with it dirt, bacteria, and other pollutants into the waterways.)

Within the first year of the permit, permittees must identify areas that are subject to flooding and implement pollution controls for these areas.

By the second year of the permit, permittees must begin sweeping parking lots twice a year and implement the removal of leaf litter and inspecting and cleaning sediment and debris from stormwater management structures, catch basins, and outfalls yearly.

Starting at the end of the first year of the permit, permittees must begin submitting annual reports to DEM describing the steps they’re taking to meet the terms of the permit.

Precipitation in an urban or suburban area that does not evaporate or soak into the ground but instead runs across the land and into the nearest waterway is stormwater runoff. This runoff can transport harmful pollutants like fertilizer, pet waste, chemical contaminants like pesticides, leaking fuel, motor oil, litter, and sediment such as dirt and sand. This mix of nutrients and contaminants can fuel the growth of harmful algal blooms that reduce oxygen levels; cloud the water; and produce toxins that can kill exposed fish, mammals and birds, and may cause human illness or even death in extreme cases. These harmful algal blooms result in pond closures, beach closures, shellfish closures, and many other water quality related problems if left untreated.

Examples of mitigation plans to reduce runoff includes leaf litter pickup, parking lot sweeping, planting trees, and reducing pavement or using pervious pavement such as porous asphalt and concrete, interlocking pavers, and plastic grid pavers, allowing rain and snowmelt to seep through the surface down to underlying layers of soil and gravel.

To date, pollutants in runoff within the watershed have resulted in elevated levels of phosphorus and fecal coliform and low dissolved oxygen, contributing to harmful algal blooms (cyanobacteria), and frequent closures of the ponds. As a result, the public has been prohibited from recreational use of the ponds. Since 2011, there have been approximately 20 public health advisories related to cyanobacteria blooms in Mashapaug, Spectacle, and Tongue ponds, often stretching many months at a time. The area surrounding the Mashapaug Watershed is located in a heavily-paved urban corridor and is an environmental justice focus area.

The neighborhoods near the ponds have endured legacy pollution and are disproportionately overburdened by the negative impacts of urban stormwater pollution. The ponds are predominantly surrounded by impermeable asphalt and concrete surfaces, which have led to significant stormwater runoff. Mashapaug Pond is listed by DEM as impaired by excess algal growth, low dissolved oxygen levels, polychlorinated biphenyls (PCBs) in fish tissue, and fecal coliform. Since at least 1998, Mashapaug and Spectacle ponds have been listed on Rhode Island’s 303(d) List of Impaired Waters.

For more information on DEM programs and initiatives, visit www.dem.ri.gov. Follow DEM on Facebook, Twitter (@RhodeIslandDEM), or Instagram (@rhodeisland.dem) for timely updates.