What’s lurking in local ponds?

Water Quality Concerns Afloat in R.I. Lakes

By FRANK CARINI/ecoRI.org News staff

The state Department of Environmental Management (DEM) recently released a report on the condition of Rhode Island’s 237 freshwater lakes, ponds and reservoirs, finding that 59 of these bodies, covering about 24 percent of the 20,749 total acres, are polluted.

In fact, bacterial contamination from enterococci, rod-shaped bacteria found in the human intestine and a good indicator of the presence of human waste, and fecal coliform are swimming around in many of these waters, including Mashapaug Pond and Roger William Park Ponds in Providence, Valley Falls Pond in Central Falls, Slater Park Pond in Pawtucket, Omega Pond in East Providence, Print Works Pond in Cranston, Sandy Pond in Warwick and the Kickemuit Reservoir in Warren.

Lakes, ponds and reservoirs cover 20,749 acres
of the Rhode Island landscape, and
data is available to assess water quality in about
75 percent of this statewide acreage.
(Graphic courtesy of DEM)

This contamination from human waste — via failing septic systems and outdated cesspools, overrun wastewater treatment facilities and malfunctioning sewer infrastructure — animal waste and other sources render this water bodies unable to meet federal water quality standards.

The DEM report, entitled “Rhode Island Freshwater Lakes and Ponds: Aquatic Invasive Plants and Water Quality Concerns” (pdf), also noted that some of these bodies have multiple water quality impairments. These impairments include fish tissue contamination — primarily mercury — nutrient enrichment, metals and pathogens. Water quality restoration studies have been completed to identify the pollutant loading reductions needed to mitigate one or more impairments on 34 of the 59 bodies, according to the DEM.

“Our lakes and ponds supply drinking water for the majority of Rhode Island residents and are highly valued resources for active and passive recreation,” DEM Director Janet Coit said. “This report will help ensure an informed discussion as we work to protect the state’s freshwater resources.”

The declining condition of Rhode Island’s lakes and ponds haven’t gone unnoticed by the public. During the past few years, an increasing number of lake associations and residents have contacted the DEM about nuisance conditions created by the growth of aquatic invasive plants. The organization Save The Lakes, formed in 2008, is a reflection of that concern.

All freshwater bodies in the state are having some type of difficulty, according to Judy Colaluca, president and co-founder of Save The Lakes. The problems range from runoff pollution from impervious surfaces, development pressures, trash and litter pollution, failed cesspools and septic systems, lawn fertilizers and invasive plants.

In fact, aquatic invasive plants have been documented as a widespread problem in many of the state’s lakes and ponds. A review of information on the presence or absence of aquatic invasive species in 133 bodies found that 80 are infested with one or more invasive plant. A total of 13 different species have been detected, with milfoil and fanwort being the plants most commonly found, according to the DEM report.

Aquatic invasive plants create dense vegetative growth that interferes with the desirable uses of lakes and has been documented by researchers to reduce lakeside property values as the infestation progresses, according to DEM officials. The occurrence of aquatic invasive plants in Rhode Island lakes is similar to that documented in Connecticut and Massachusetts, they said.

Blue-green algal blooms, produced by naturally occurring cyanobacteria and often fueled by excess nutrients, are an emerging water quality management and public health issue in Rhode Island’s lakes and ponds. These blooms may be harmful to people and animals, according to the state Department of Health (DOH). They often produce a scum on the water’s surface and may cause the water to become a striking green.

Cyanobacteria produce a number of nuisance compounds, including natural toxins. In sufficient quantity, these toxins can make a water body unsafe for recreational and other uses, such as a drinking water supply. 

Contact with cyanobacteria can cause skin or eye irritation. Ingesting small amounts can cause gastrointestinal symptoms; ingesting large amounts may cause liver or neurological damage. Children are more susceptible to the effects of cyanobacteria than adults. Dogs can get very ill and even die from ingesting cyanobacteria, either directly ingesting it or licking if off their fur, according to the DOH.