Salt Ponds Watershed
The Salt Ponds Region, comprised of portions of Westerly, Charlestown, South Kingstown, and Narragansett Indian lands, runs along most of Rhode Island’s south shore. It includes several large coastal salt ponds and some brackish ponds, from west to east: Winnapaug Pond, Quonochotaug Pond, Ninigret Pond, Green Hill Pond, Trustom Pond (brackish), Card Ponds Salt Ponds (brackish), Potter Pond and Point Judith Pond. Land use in the watershed is primarily residential, with the heaviest concentrations of development occurring along the coastlines of the ponds.
Salt ponds are formed and continuously reformed by the interaction of coastal processes, including erosion, sediment transport, and gradually rising sea level. As the ocean waters rise—a phenomenon under way since the last Ice Age—they spill into depressions in the landscape, creating shallow estuaries. Meanwhile, longshore currents transport sand eroded from wave-battered headlands— higher, more durable points along the coast—and deposit it in low-lying areas. As the sand accumulates, it forms a barrier spit, or beach, that separates the pond from the ocean waters. In most cases, a tidal inlet, or breachway, is created by either storm waves washing over the sand spit or from the pressure of fresh water swelling the pond from the landward side. This inlet provides a connection between the pond and the sea through which sediment and water are transferred. The interchange is usually seasonal: Winter storms choke the inlet with wave-churned sand, and spring runoff from streams and groundwater swells the pond until it bursts through the barrier. The more a pond is open to the sea, the more it is flushed with seawater, resulting in a higher salinity. Salt ponds are also greatly influenced by powerful coastal storms. During severe winter storms, surging waves hurl sand eroded from the front of the barrier over the spit into the seaward side of the pond. The overwash from these strong waves spills water behind the newly deposited sand. It is during this process that salt ponds retreat steadily landward. For several thousand years, Rhode Island’s entire barrier spit-coastal pond system has been migrating north—and will continue to do so.
In spite of the loss of a number of brackish-water (slightly salty water) fisheries, such as alewife and oysters, due to permanent breaching, the ponds today are still highly productive and popular fishing grounds. Recreationally fished species include summer flounder, striped bass, winter flounder, shad, white perch, mackerel, and tautog. Among shellfish, quahog is by far the most common species recreationally collected in the ponds, but (depending on the pond and the season) steamers, blue mussel, and bay scallop may also be found. Commercially fished species include quahog, steamers, oyster, eel, bay scallop, and mussel. In addition, green crab is harvested specifically for the bait industry, while blue crab is harvested recreationally. Not only are the salt ponds valuable spawning and nursery grounds for many aquatic species, but they are also prime feeding areas for migrating waterfowl, including Canada goose, greater scaup, and great blue heron. Even the endangered piping plover has taken advantage of the resources provided by the salt ponds. Plant life is also an important component of the salt pond system. One of the most vital species of aquatic plant is eelgrass (Zostera marina), a form of seagrass that functions as a haven for fish larvae and shellfish. Some scientific research suggests that increased nutrient pollution from sewage disposal systems and fertilizer usage may be decreasing the extent of eelgrass in the ponds. The nutrients contribute to algal blooms that limit the amount of available sunlight, which the plant needs to survive.
When humans first began to settle in the Northeast, they established a permanent village on the edges of a salt pond. Archaeologists believe this village, set up on Block Island’s Great Salt Pond by ancestors of the Manissean Indians, may have been the first year-round settlement in the Northeast. Additional early human activity existed in the form of a fishing encampment created by Indians on the west side of Potter Pond between 3,000 and 2,500 years ago. What made these early camps and villages unique was the existence of their thriving maritime economy 1,500 years before the first known agricultural settlement in the area. In later years, the Narragansett Indians utilized the many resources of the pond during the summer months to fish for food and gather quahog for wampum—purple beads used for jewelry, gift-giving, and exchange. European colonial settlers also fished the ponds, as well as farmed the open space surrounding the salt pond area. The colonial farmers often hand dug channels from the ponds to the ocean to drain their fields after spring rains. More deliberate alteration of the ponds came with modern commerce. Temporary breachways were dredged to accommodate large boats used to bring both agricultural and fishing products to market. But because salt pond systems are dynamic, artificial breaching was only a temporary solution. Natural processes refilled the dredged channels, prompting the construction of permanent breachways in most of the south shore ponds during the 1950s. The resulting uninterrupted flow of seawater into the ponds increased salinity sufficiently to change the habitat and thus the makeup of the ponds’ fish populations.
Like coastal areas all over the country, the salt pond region has seen both increased tourism and rapid residential growth since the real estate boom of the mid-1980s. In the 10 years from 1990 to 2000, the average population of the four towns surrounding the salt ponds increased by 12.5 percent, nearly three times the state’s growth. Charlestown grew the most, by 21 percent. Commercial development has also been extensive, particularly around Point Judith Pond, which has the village of Wakefield at its head and Galilee, Rhode Island’s largest fishing port, at its mouth. And the number of tourist-related businesses, such as hotels, shops, and restaurants, is increasing throughout the salt pond area—not surprising in light of the fact that the south shore barrier beaches rank as Rhode Island’s number-one recreational resource.
Except for the village of Wakefield and the port of Galilee, the majority of the pond region is not sewered. Instead, residents use individual sewage disposal systems (ISDS) for sewage treatment. In some cases inadequate, antiquated, or poorly maintained sewage disposal systems allow wastewater to contaminate groundwater. Moreover, even a properly maintained septic system contributes nitrate to the groundwater. As residential development increases and more and more septic systems are constructed in a limited geographic area, nitrate contamination could become a significant problem. Nitrate from both septic systems and lawn fertilizers contributes to eutrophication, a process that occurs when a body of water is excessively loaded with nutrients, promoting overgrowth of algae. Bacterial decomposition of this algae depletes the water of oxygen. When eutrophication is severe, fish and other marine organisms can suffocate. Another threat from septic systems is the release of disease-causing viruses and bacteria that are carried in human feces. Fecal coliform— commonly referred to as E. coli—is the most prevalent bacteria detected in contaminated shellfish. Bacterial contaminations have resulted in several permanent shellfish closures in the salt ponds, including upper portions of Point Judith Pond, eastern portions of Ninigret Pond, and all of Green Hill Pond.
Green Hill Pond and Ninigret Pond, two salt ponds located in southern Rhode Island, have been identified by DEM as being impaired by pathogens (i.e., bacteria). Teal and Factory Brook, tributaries to Green Hill Pond, have also been identified as being impaired by pathogens. During the summer of 1999, DEM staff carried out preliminary water quality monitoring in the ponds, as well as the two tributaries. Dry and wet weather monitoring continued in 2000, and a public meeting was held in August to present the information collected so far to interested stakeholders. Two more wet weather surveys are planned for the spring/summer of 2001. The data will be used to support the development of a restoration plan, known as a Total Maximum Daily Load (TMDL), for the two ponds and freshwater streams. The goal of the TMDLs is the eventual reopening of the ponds to shellfishing. DEM has partnered with the Salt Ponds Coalition and the University of Rhode Islands Cooperative Extension to enhance public awareness of water quality issues and to support the voluntary inspection and maintenance of septic systems that may impact water quality in the ponds. URI is also providing DEM with technical assistance and landuse pollution risk maps to support TMDL development.
The Salt Pond Watchers, founded in 1985, was the first marine, volunteer, water quality monitoring group in Rhode Island. In 1993, the Pond Watchers merged with the Salt Ponds Coalition. Pond Watchers sample the salt ponds biweekly from May to September, and analyze these samples at the University of Rhode Island's Microbiology Department. The resulting water quality data is supplied to the state's Department of Environmental Management and coastal area communities. These agencies use this data to help make decisions regarding subsequent public use of the salt ponds.
This document addresses fecal coliform impairments to Green Hill Pond, two of its tributaries, Factory Pond Stream and Teal Pond Stream, and a portion of Ninigret Pond, all located in the Towns of South Kingstown and Charlestown, Rhode Island. Green Hill Pond, Ninigret Pond, Factory Pond Stream and Teal Pond Stream have been listed on Rhode Island's 2002 303(d) List of Impaired Waters. A Total Maximum Daily Load (TMDL) is developed by locating all pollution sources, determining the amount of pollution a waterbody can accept and still meet water quality standards, and outlining an implementation strategy to abate pollution sources.
The study area for this TMDL includes the entire Green Hill Pond watershed and the impaired areas in easternmost Ninigret Pond, located in the Towns of South Kingstown and Charlestown, Rhode Island and several small freshwater tributaries (Figure 2.1). Factory Pond Stream, Teal Pond Stream and several unnamed streams discharge to Green Hill Pond.
As reported in the State's 2002 303(d) list of impaired waterbodies, Green Hill Pond(0.66 mi2), and an adjacent portion of Ninigret Pond (0.158 mi2), Factory Pond Stream and Teal Pond Stream are impacted by fecal coliform bacteria. Green Hill Pond, Ninigret Pond, Factory Pond Stream and Teal Pond Stream are listed as Group 1 waterbodies and given the highest priority for TMDL development.
Green Hill Pond and the adjacent portion of Ninigret Pond are designated as Class SA waterbodies by the State of Rhode Island. Class SA waters are designated for shellfish harvesting, direct human consumption, primary and secondary contact recreation activities, and fish and wildlife habitat. They shall be suitable for aquacultural uses, navigation and industrial cooling. Teal Pond Stream, Factory Pond Stream and their tributaries are designated Class A waterbodies by the State of Rhode Island. Class A waters are designated as a source for public drinking water supply, for primary and secondary contact recreation and fish and wildlife habitat and shall be suitable for compatible industrial processes and cooling, hydropower, aquacultural uses navigation and irrigation and other agricultural uses. Class SA and Class A waters should have good aesthetic value.
Numeric Water Quality Criteria
The fecal coliform water quality standard for Green Hill and the adjacent portion of Ninigret Pond is a geometric mean value of 14 fc/100 ml with not more that 10% of the samples exceeding an value of 49 fc/100ml. These criteria are applicable for Green Hill and Ninigret Ponds and at the mouths of all entering tributaries. The fecal coliform water quality standard for Teal and Factory Pond Streams is a geometric mean value of 20 fc/100 ml with not more than 10% of the samples exceeding a value of 200 fc/100 ml. These criteria are applicable for the reaches above the mouths of Teal and Factory Pond Streams.
Rhode Island 's antidegradation policy requires that, at a minimum, the water quality necessary to support existing uses be maintained (see Rule 18, Tier 1 in the State of Rhode Island's Water Quality Regulations). If water quality for a particular parameter is of a higher level than necessary to support an existing use (i.e. bacterial levels are below Class SA or A standards), that improved level of quality should be maintained and protected (see Rule 18, Tier 2 in the State of Rhode Island's Water Quality Regulations). Because water quality in Green Hill and Ninigret Ponds and in Factory and Teal Pond Streams violates water quality standards, Tier 2 does not apply.
Organizations & Links
Salt Ponds Coalition
The Salt Ponds Coalition (SPC) serves as steward for the Rhode Island coastal salt ponds, which contribute substantial revenues to tourism and fishing—the economic lifeblood of communities in Southern Rhode Island. The ponds are rich spawning, nursery and feeding grounds for fish and wildlife, but signs that their ecosystems may be in serious trouble include local shellfishing closures, increasing seaweed, and higher levels of bacteria. The SPC was incorporated in 1986 and merged with the Rhode Island Salt Pond Watchers in 1993. The SPC is a 501(c)(3) and was recognized by the Rivers Council in 2004. The SPC has a part-time executive director and is governed by a Board of Directors. The SPC has 500 members.
The SPC is working with a variety of state and federal agencies on projects to improve the salt ponds’ water quality, habitats and fisheries. The state is undertaking a watershed management plan for two of the nine lagoons, Green Hill and Ninigret Ponds, in an effort to reduce pollution. Solutions under consideration include stormwater treatment and advanced, nitrogen-reducing home wastewater systems. State and federal agencies are dredging the Ninigret Pond tidal inlet, or breachway, in an attempt to restore seagrass habitat there, and are working to restore bay scallops in several of the ponds by developing “spawner sanctuaries” where the shellfish can reproduce.Elise Torello, Executive Director
Salt Ponds Coalition
P.O. Box 875
Charlestown , RI 02813