By FRANK CARINI/ecoRI News staff
In the latest report documenting Rhode Island’s impaired fresh waters, 67 water bodies that weren’t previously listed have been added, including Herring Brook, Mill Pond, and part of the Pawcatuck River.
The cause of impairment in 50 of those water bodies is enterococcus. Mercury in fish tissue was the impairment in the 17 other newly listed waterways, including Echo Lake (Pascoag Reservoir), Burlingame Reservoir, and Deep Pond.
However, bacterial contamination from enterococci, rod-shaped bacteria found in the human intestine and a good indicator of the presence of human waste, is the leading contaminant in Rhode Island’s impaired fresh waters.
Of the 24 water bodies that remain on the updated list from 2014, 10 are impaired by the presence of enterococci. The impairments for the other 14 water bodies include iron, mercury in fish tissue, dissolved oxygen, phosphorus and copper.
Contamination from human waste — via cesspools, failing septic systems, overrun wastewater treatment facilities, and malfunctioning sewer infrastructure — animal waste, and other sources has defiled 60 of the state’s 91 impaired waters and rendered them unable to meet federal water-quality standards, according to the latest report from the Environmental Protection Agency (EPA).
Enterococci and fecal coliform levels are used as indicators of the presence of fecal material — human or animal — in drinking and recreational waters. Both indicate the possible presence of disease-causing bacteria and viruses. Such pathogens may pose health risks to people swimming or fishing.
Infections caused by pathogen-contaminated waters include gastrointestinal, respiratory, eye, ear, nose, throat and skin diseases, according to the EPA.
Besides possibly impacting public health, such contamination can degrade aquatic ecosystems and result in the closure of shellfish beds and beaches. Drinking-water supplies can become impaired.
Documenting problems, improvements
To help remediate the state’s impaired waters, Rhode Island's Department of Environmental Management (DEM) relies on something called the Total Maximum Daily Load (TMDL) — an enforceable document approved by the EPA every two years. This working document establishes the allowable bacterial contributions for Rhode Island’s surface waters, provides documentation of impairment, and specifies the actions needed to reduce contamination.
The purpose of the TMDL is the “attainment of water quality standards” by the establishment of regulatory requirements and recommendations for municipalities and other stakeholders to address pollutant sources contributing to impairment. It encourages community-based approaches.
Rhode Island’s latest report also has identified water bodies that can be removed from the list of impaired waters, because available monitoring data show that water-quality criteria are now being met.
Among the 25 water bodies showing improved water quality after investments in pollution abatement infrastructure and practices are: Mount Hope Bay, Greenwich Cove in East Greenwich, Cedar Swamp Brook in Johnston, and the lower Woonasquatucket River in Providence, North Providence and Johnston.
Thermal discharges from the Brayton Point Station in Somerset, Mass., once the largest fossil-fuel burning power plant in New England, led to elevated water temperatures and reduced fish abundance in Mount Hope Bay, and inclusion on the state’s impaired list in 2000.
To address the thermal impacts, the power plant converted to closed-cycle cooling in May 2012. Available data from June 2012 to December 2015 following the plant’s conversion document compliance with water-quality standards for temperature in the Rhode Island portion of Mount Hope Bay. Brayton Point Station ceased operation in June 2017.
For Greenwich Cove, water-quality data reveal that the cove’s bacteria concentrations now meet safe swimming levels, according to DEM. Water-quality improvements here are attributed to the installation of 23 infiltrating catch basins in the Harbor District, stormwater management improvements, the elimination of wastewater discharges caused by failing onsite wastewater systems at a local marina and senior living facility, and the removal of a sanitary sewer connection to a storm drain at a mill property.
Water-quality improvements in Cedar Swamp Brook, a stream that flows next to the Central Landfill, are attributed to operational improvements at the landfill, such as improved erosion controls, the installation of a treatment system to remove ammonia and iron, and the permanent relocation of the stream. Cedar Swamp Brook flows to the Pawtuxet River.
In the lower Woonasquatucket River, water-quality improvements are evident from the improved condition of aquatic organism communities living in and on the bottom of the river, according to DEM. Infrastructure investments that contributed to the observed improvement in the river’s ecological health are treatment upgrades at the Smithfield wastewater treatment facility, stormwater improvements at Metals Recycling in Johnston, and completion of the Narragansett Bay Commission’s Phase II combined sewer overflow (CSO) abatement project. This phase included elimination of seven CSO outfalls and a significant reduction in the discharge of combined sewage and stormwater at seven other CSO outfalls that discharge to the Woonasquatucket River.
Causes and solutions
In water bodies, both marine and fresh, the acceptable level of enterococci contamination is low. Suitable levels for enterococci in fresh water, from a single sample reading, should be between 61 and 151 colony-forming units (cfu) per 100 milliliters of water, according to the EPA. The Rhode Island standard is the low end of that range, and readings can fluctuate depending on many variables.
Enterococci, fecal coliform, and other potentially harmful bacteria may enter surface waters because of:
Malfunctioning wastewater treatment plant. In Rhode Island, in addition to the 19 major and two minor municipal wastewater treatment plants, there are three major and three minor industrial wastewater treatment plants that have the potential to discharge untreated or partially treated wastewater.
Development. Stormwater runoff is water from rain or snowmelt that flows over impervious surfaces, such as roofs, asphalt, and concrete, isn’t absorbed into the ground and thus isn’t naturally filtered. As this runoff moves, it picks up and carries away natural and anthropogenic pollutants and eventually deposits them into surface waters. Stormwater runoff is one of the leading sources of impairment to the nation’s waters.
Sanitary sewer overflows. These discharges of untreated wastewater from sewer systems are caused by clogged or cracked sewer pipes, by excess infiltration and inflow, by undersized piping and/or by equipment failure.
Illicit discharges to stormwater systems. Examples of illicit discharges commonly seen in urban communities in Rhode Island include direct discharges, such as sanitary wastewater pipes connected from a home to a storm drain, and indirect illicit discharges, such as a damaged sanitary sewer line that is leaking wastewater into a cracked storm sewer line.
Boats. They have the potential to discharge harmful bacteria in sewage from installed toilets and greywater — drainage from sinks, showers and laundry. Sewage and greywater illegally discharged from boats can contain pathogens, nutrients, and chemical products that can lead to water-quality violations.
Onsite wastewater treatment systems. When properly installed, operated, and maintained, such systems — i.e., septic systems — effectively reduce bacteria concentrations in sewage. However, poor maintenance, overloading, improper design and/or construction, and age can result in system failure and the release of bacteria and other pollutants into surface waters.
Wildlife and pets. Fecal matter from wildlife can be a significant source of bacteria in some watersheds, especially when human activities, such as the feeding of wildlife and habitat modification, result in the congregation of wildlife. Concentrations of geese, gulls, and ducks are of particular concern because they often deposit their waste directly into surface waters. In fact, it’s illegal to feed waterfowl.
Pet waste also can be a significant contributor. For example, each dog is estimated to produce 200 grams of feces daily, and pet feces can contain up to 23 million fecal coliform colonies per gram. If pet waste isn’t properly disposed, these bacteria can be washed off the land and transported to surface waters by stormwater runoff.
Agriculture. Agricultural land includes dairy farming, raising livestock and poultry, growing crops, and keeping horses and other animals for pleasure and/or profit. Activities and facilities associated with agricultural land use can be sources of bacteria impairment. Communities, farmers, horse owners, and others who confine animals are largely responsible for mitigating bacteria pollution. Direct deposition of fecal matter from farm animals standing or swimming in surface waters, and the runoff of farm animal waste are considered the primary mechanisms for agricultural bacteria pollution in surface waters.