Pollutants

In the 1700s Apponaug and Greenwich coves saw the advent of seaports and shipbuilding centers that gave rise to manufacturing mills of the 1800s. These mills discharged untreated textile and metal waste and sewage into the bay. The surface of Apponaug Cove is said to have bubbled with red and yellow suds from mill chemicals. Anne Holst, a former Rhode Island Department of Environmental Management (RIDEM) conservation officer, notes that "kids in the 1930s and 1940s used to work (Greenwich) Cove for extra money, but they never knew what color the shellfish were going to be-it all depended on what color the Bleachery (a former East Greenwich fabric dyeing company) was using that day. They'd have to hose it all off."

Yet, the impacts of early industry on bay water paled compared to the later effects of suburban development. After World War II, returning soldiers took advantage of a federal bill that enabled them to buy new homes in suburban neighborhoods. The homes were often built on half-acre lots and discharged sewage that seeped into the water table and the bay. The problem worsened as summer cottages in Oakland Beach, Nausauket, Buttonwoods, and Potowomut, which were equipped to handle seasonal septic needs, became year-round homes. Automobile pollution also became a problem as rain washed increasing amounts of oil, chemical, and metal deposits off highways and parking lots into the bay.

As land is developed, it is usually altered in some way that makes precipitation run off it more quickly. Paving is a common example of this. When rain falls on undeveloped land such as a meadow, the water is slowed by plants, and generally sinks into the soil. In contrast, when rain falls on asphalt, concrete, or any other impermeable surface, it runs off into the nearest storm drain. Hence, this water—and any materials it picks up along the way—is know as runoff—specifically, stormwater runoff or urban runoff. Even lawns, while more permeable than areas with larger and denser vegetation, may promote runoff.

The pollutants that may be found in runoff include organic contaminants such as oil and gasoline. Fertilizers (nutrients) and pesticides (also organic contaminants) may also be washed off lawns and carried into storm drains. The storm drains carry runoff to pipes that usually discharge into a nearby water body, such as Tuscatucket Brook or Greenwich Bay itself. Sediment and road salt may also be carried in runoff. In addition, materials such as used motor oil are sometimes deliberately poured directly into storm drains. In some cases, illegal sewer hookups may tie directly into storm drains, contributing nutrients and bacteria to local water bodies. Bacteria may also come from failed septic systems (see below), which are common in Warwick.

SEPTIC SYSTEMS

A high percentage of shoreline homes on Greenwich Bay have outdated, inefficient, and overburdened septic systems. In Warwick, sewer lines are in place in Oakland Beach and Apponaug, but many homes are not connected to the sewers. A cross-section of a failing septic system is shown below.

(1) Waste enters the system through household pipes.
(2) Solids settle in the septic tank, which should be pumped out every two to three years.
(3) Normally, water drains into a leaching field, where perforated pipes are generally surrounded by crushed stone. The leaching field holds water until it drains into surrounding soil. Bacteria are then filtered out by the soil, and the water continues to seep down to the water table.
(4) If the system is not maintained, the septic tank fills, and some solids may enter the pipes and leaching field. From the leaching field, water may also be forced upward, where it is carried by surface runoff, or pushed downward into groundwater without spending enough time in the soil to be filtered.
(5) Bacteria eventually find their way into Greenwich Bay.

Even properly functioning septic systems do not remove many nutrients, such as nitorgen, from wastewater. Excess nitrogen in a body of water may lead to a number of problems, including algae blooms and low oxygen levels.

TRIBUTARIES

Streams that empty into Greenwich Bay may be major source of pollution if they are affected by a large source themselves. A good example is Hardig Brook, which the Food and Drug Administration found to be the largest single pollution source to the bay, largely because of bacteria and nutrients washing into the brook from manure at a dairy farm, and from direct sewage discharge at a mill in Apponaug.

1. Hardig Brook
2. Hunt-Potowomut River
3. Baker Creek
4. (Drain pipe in headwall at Norton's Shipyard)
5. Small creek west of Warwick Ave., just downstream from sewage lift station.
6. Maskerchugg River

MARINAS AND BOATING ACTIVITIES

Over 3,000 boats are docked or moored in Greenwich Bay and its coves. Although there are still many unknowns, boating activities are known to have a number of potential effects on water quality. Pollutants from boats and marinas may include:

1. Sewage (nutrients and bacteria) - Pumped treated or untreated directly from boats.
2. Sediments - From parking lots, erosion, and sanding of boats.
3. Heavy metals - In boat paint particles from sandblasting and boat washing; metal shavings from engine oils; bilgewater; and runoff from maintenance and repair areas.
4. Hydrocarbons - From boat engines, fueling docks, engine repair or maintenance activities, dredging, and stormwater runoff.
5. Others - Solvents, antifreeze, TBT (tributylin, used in boat bottom paint to prevent fouling organisms from growing on the boat), surfactants (a component of most detergents), and acids and alkali from boat batteries and other cleaning compounds. These may be toxic to marine life.

WASTEWATER TREATMENT PLANT

Much of Warwick remains unsewered, but the sewage from those houses and businesses that are hooked to the sewer system goes the city plant, which is located west of Route 95. The plant empties treated wastewater into the Pawtuxet River, which flows into Narragansett Bay at the Warwick/Cranston border.Wastewater from treatment plants has not been found to be a major source of bacterial pollution in Greenwich Bay. Researchers are very interested right now in finding out whether some pollutants may be carried into Greenwich Bay by water that flows down from the Providence River.

ORGANIC POLLUTANTS

"Organic" describes chemical compounds that contain carbon, hydrogen, and oxygen. Organic pollutants include petroleum products such as oil and gasoline, pesticides, solvents, cleaning agents, PCBs (or polychlorinated biphenyls, which were once used in electrical transformers), and many other chemical compounds.

Rainwater washing over land picks up these pollutants from roads, parking lots, and commercial and industrial activities. The pollutants then enter the bay from storm drains or when the water flowing over land carries them directly into the water. Organic pollutants are also found in household waste such as cleaning products, and may make their way to the bay after passing through wastewater treatment plants or septic systems.

Once the organic pollutants enter the sediments at the bottom of the bay, they can remain there for decades. But they can re-enter the water column if storms, dredging, or other "disturbances" cause the stirring of the sediments.

Some of these pollutants have been found to cause cancer and other health effects in humans. In high concentrations, they are toxic to freshwater and saltwater organisms.

Human and animal wastes are also considered organic pollutants.

HEAVY METALS

Heavy metals such as copper, lead, zinc, chromium, and cadmium, are common in urban runoff. They may be washed down industrial drains and end up in septic systems or at wastewater treatment facilities, or they may run off parking lots and roads, eventually making their way to Greenwich Bay. Heavy metals present a variety of health risks if ingested by humans. They are hazardous to freshwater and saltwater organisms.

The presence of textile mills, such as the one seen here, contributed to years of hazerdous metal and other pollutants into the bay.

BACTERIA

Bacteria, which are found in human and animal wastes, enter Greenwich Bay from leaking septic systems, broken sewer lines, illegal sewage "tie-ins" to storm drains, and animal feces.

These bacteria can result in contamination of shellfish, which in turn can cause illness in those who eat the shellfish. When levels of bacteria in the water are high, people can become sick from direct contact with the water, for instance, from swimming.

The decision to close Greenwich Bay to shellfishing in 1992 resulted from high levels of fecal coliform bacteria. Fecal coliform bacteria are present in human and animal waste, and are used as an indicator that this waste is present in the water. They are not in themselves harmful bacteria.

NUTRIENTS

Nitrogen and phosphorous are primary components of fertilizers, and are also found in sewage. They enter Greenwich Bay through stormwater runoff, speptic systems, and through wastewater treatment plants. Nitrogen is the nutrient of most concern in saltwater environments.

When nutrients enter the water in large amounts, they can contribute to a process known as eutrophication, which can result in a rapid increase in plant growth: "blooms" of algae or phytoplankton. When these plants die, bacteria in the water begin to break them down. Since there is now more food for the bacteria, the bacteria multiply, and therefore use up large quantities of dissolved oxygen in the water. This can lead to a condition known as hypoxia, or low oxygen. Low oxygen levels in the water are dangerous to all animals in the bay, especially fish and other animals that need relatively high levels to survive.