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RI Department of Environmental Management
235 Promenade Street, Providence, RI 02908
(401) 222-2771 TDD/(401) 222-4462
DEM ANNOUNCES UPCOMING MEETINGS TO DISCUSS NEW RESTORATION STUDIES AND STRATEGIES FOR IMPROVING WATER QUALITY IN TEN PONDS
The two draft water quality restoration studies, otherwise known as Total Maximum Daily Loads (TMDLs), address phosphorus and phosphorus-related impairments, such as low dissolved oxygen and excessive growth of aquatic plants and algae in ten of the state's freshwater ponds. One study specifically focuses on Mashapaug Pond in Providence; the other evaluates nine ponds located in urban and suburban settings throughout the state. Those are: Almy Pond in Newport; Brickyard Pond in Barrington; Gorton Pond, Sand Pond, and Warwick Pond in Warwick; North Easton Pond in Middletown/Newport; Roger Williams Park ponds in Providence; Spectacle Pond in Cranston; and Upper Dam Pond in Coventry.
Though the Mashapaug Pond restoration study was prepared as a separate document from the eutrophic ponds restoration study, they all address the same kinds of water quality problems. Additionally, Mashapaug Pond is hydrologically connected with two ponds included in the eutrophic ponds restoration study — Spectacle Pond and the Roger Williams Park ponds.
The eutrophic ponds are small and range in area from 20 to 131 acres. Their associated watersheds are generally less than 800 acres in area. These impairments affect both recreational uses and ecological health of the ponds, and in the case of North Easton Pond, may result in higher drinking water supply treatment costs.
Studies Establish Maximum Pollutant Loads Ponds Can Handle and Still Meet Standards
Water quality restoration studies are mandated by the federal Clean Water Act and establish the maximum pollutant load that a waterbody can assimilate and still meet water quality standards. The Mashapaug Pond study, prepared by DEM, utilizes the results of water quality sampling and computer modeling completed by Environmental Protection Agency contractor, TetraTech, Inc. The model was used to determine the phosphorus concentrations necessary to mitigate excess algal growth and low dissolved oxygen conditions in the pond.
In preparing the restoration study for the nine eutrophic ponds, DEM utilized data collected by URI Watershed Watch volunteers as well as limited data collected by DEM staff to characterize water quality conditions of the ponds. The study reports that the ponds fail to meet water quality standards for phosphorus and in some cases the related impairments of excess algal growth and low dissolved oxygen. A simplistic model was used to determine pollutant reductions necessary for these ponds to meet their target phosphorus concentrations. For both restoration studies, DEM utilized the results of watershed and shoreline inspections including the identification of stormwater outfalls discharging to the ponds and available pollution source data as well as in-pond phosphorus data to identify pollution sources and determine necessary pollution abatement activities.
Elevated phosphorus concentrations originate from within the watershed, impacting the ponds mainly via tributaries and stormwater outfalls. Primary sources of phosphorus include stormwater runoff, waterfowl, and erosion. The cumulative impacts of stormwater runoff degrade water quality and necessitate a watershed-wide pollution reduction approach directed at both point and nonpoint sources of pollution. In addition, available data suggests that internal cycling of phosphorus deposited in the bottom sediments of some lakes may also contribute to water column phosphorus concentrations. In-lake management techniques may be necessary in some lakes to control this source of phosphorus.
The regional meetings will focus on the ponds located in the vicinity of the meeting locations. The first meeting, focusing on Brickyard Pond, will be held on Tuesday, April 17 from 6:30 p.m. to 8:30 p.m. at the Barrington Public Library at 281 County Road in Barrington.
The second meeting will be held on Tuesday, April 24 in Middletown, and will focus on Almy and North Easton (Green End) Ponds. It will be held from 6:30 p.m. to 8:30 p.m. at the Middletown Town Hall at 350 East Main Road.
The Warwick ponds - Gorton, Sand, and Warwick - and Coventry's Upper Dam Pond will be discussed on Monday, April 30, from 6:30 p.m. to 8:30 p.m. at the Warwick Sewer Authority meeting room at 125 Arthur W. Devine Boulevard in Warwick.
Mashapaug and Spectacle Ponds and the Roger Williams Park ponds will be discussed at a meeting on Wednesday, May 2, from 6:30 p.m. to 8:30 p.m. in the cafeteria at DEM headquarters, 235 Promenade Street in Providence.
Copies of the executive summary from the draft studies will be available at the meetings. The entire text of the documents is available online at DEM's website, www.dem.ri.gov, by clicking on "Topics", then "Water Quality", then "Restoration Studies". Copies are also available by contacting Scott Ribas by phone at 222-4700 ext. 4413 or by e-mail at firstname.lastname@example.org. DEM will accept written comments on both studies until May 31.