Raymond Wright
University of Rhode Island
Department of Civil and Environmental Engineering

• What pollutants, and how much of each, enter Greenwich Bay directly through storm drains that empty into the Bay?
  
  
• How much enters the Bay when it rains or snows? How much enters when the weather is dry?
  
  
• Where are the "hot spots" that are the sources of the greatest pollution? What land uses in the area may be leading to these high inputs of pollutants?
  
  
• How can we design a model that can predict when and where the greatest amount of pollution will enter the Bay?

First, Wright did an inventory of storm drains around Greenwich Bay, listing 53 in Warwick and seven in East Greenwich. The drains emptied into the main body of the Bay itself, into Apponaug, Brush Neck, Greenwich, and Warwick coves, and into Buttonwood, Carpenter's, and Tuscatucket brooks.

Next, Wright measured the amounts of fecal coliform bacteria and nutrients that were coming out of 30 selected storm drains during dry weather. During dry weather, any water coming from the outfall would have entered from the groundwater. Samples from a second set of 10 outfalls were also collected and analyzed. Results from some of these surveys showed very high levels of bacteria and nutrients. These discharges may be coming directly from several neighborhoods that do not have sewers.

The third component of the research involves wet-weather water sampling from the outfalls. This will involve sampling before, during, and after three separate storms. In order for a storm to be selected for sampling, there must be at least .3 inches of rainfall, the rain must last at least 5 hours, and it needs to be dry for at least three days before the storm.

The water samples will be analyzed for:

Water Quality Parameter	Importance
Fecal coliform	Indicates presence of human or animal waste
Nutrients, including: Dissolved nitrate and ammonia Phosphorus	Contribute to eutrophication and low oxygen levels
Total/volatile suspended solids	Measure of sediments, which may harm shellfish
Sodium and chloride	Markers of road runoff
Dissolved oxygen Biological oxygen demand	Important to oxygen modelling

These data will be used to determine which of the outfalls - "hot spots" - are contributing the most bacteria and nutrients to Greenwich Bay. Then the researchers will look at local land uses to determine which ones are the original sources of pollution.

Next, a computer model will be created for stormwater discharges to Greenwich Bay. The model will predict how much pollution - and from what sources - will enter the Bay during a given rainstorm.

Finally, the water quality data and the model will become part of the COASTMAP program. Together, all the data gathered by the Sea Grant researchers, and other researchers, can be put together in one place to help the city of Warwick, the town of East Greenwich, and the state find ways to reduce the pollution that goes into Greenwich Bay.

Rhode Island Sea Grant