Nitrogen Impacting Health of Westport River Estuary

By ecoRI News staff

Steady population growth and increased development has created an overabundance of nitrogen in the harbors, bays and estuaries of Buzzards Bay. (DEP).

Steady population growth and increased development has created an overabundance of nitrogen in the harbors, bays and estuaries of Buzzards Bay. (DEP).

WESTPORT, Mass. — The Massachusetts Department of Environmental Protection (DEP) will hold a public meeting June 23 seeking comments on a draft document identifying the need to limit and reduce nitrogen pollution in the coastal waters of the Westport River estuarine system. The meeting will be held from 4-5 p.m. in the Town Hall Annex meeting room, 856 Main Road.

The segments of the Westport River involved include: East Branch, West Branch, The Let, Westport River Harbor, Old County Road, Kirby Brook, Adamsville Brook, Angeline Creek and Snell Creek. The restoration plan for the estuary system, formulated by DEP and the University of Massachusetts-Dartmouth School for Marine Science and Technology, is proposed as part of a multiyear collaborative project intended to improve estuarine water quality in up to 70 embayments along the southeastern Massachusetts coastline.

The two coastal water bodies — East and West branches of the Westport River — with watersheds in Westport, Dartmouth, Freetown and Fall River, as well as Tiverton and Little Compton, R.I., are currently impaired by excess nutrients, mainly nitrogen. Nitrogen is the primary cause of eutrophication that chokes water bodies with harmful algae, depletes oxygen for fish and shellfish populations, destroys critical eelgrass beds needed for sustaining marine life, and reduces swimming, fishing and boating opportunities throughout the waterways of Buzzards Bay.

The plan includes seven “pollution prevention” Total Maximum Daily Load (TMDL) designations in water bodies that are hydraulically linked to impaired waters to maintain existing high-quality waters.

Steady population growth and increased development, particularly during the past several decades in southeastern Massachusetts, has created an overabundance of nitrogen in the harbors, bays and estuaries of Buzzards Bay, according to DEP. The primary controllable source of nitrogen is wastewater discharged from septic systems, stormwater runoff, leaching lawn fertilizers and discharges from agricultural land uses. Atmospheric deposition also contributes varying quantities of nitrogen.

At the June 23 public meeting, DEP staff will present a draft TMDL for limiting nitrogen to the amounts that the water bodies can absorb without violating water-quality standards and impairing uses such as fishing and recreational activities. The plan calls for reducing watershed sources of nitrogen by up to 56 percent. Most of the reductions will be from better treatment and handling of wastewater, but nitrogen from stormwater and fertilizer use should also be controlled wherever possible, according to DEP.

The major components of this effort included seven years of chemical, physical and biological studies, and the use of a water-quality model that linked the watershed to the present sources of nitrogen, the loading rates and the nitrogen concentrations in the embayment, to determine nitrogen concentrations and target nitrogen loading rates that will result in the restoration and protection of the estuarine system. This watershed modeling and TMDL analysis will serve as a planning tool for communities to implement new wastewater management strategies, according to DEP.

The public comment period ends at 5 p.m. July 25. Written comments may be submitted to: Barbara Kickham, MassDEP, Watershed Planning Program, 8 New Bond Street, Worcester, MA 01606. Electronic comments should be sent to