By ecoRI News staff
The Environmental Protection Agency (EPA) recently approved the Westport River total maximum daily load (TMDL) of nitrogen allowable in the estuary, as submitted by the Massachusetts Department of Environmental Protection (DEP) in early April.
The TMDL sets the level to which the state must reduce nitrogen inputs to restore the river to a healthy state.
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 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.
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.
For more than 20 years, the Westport River Watershed Alliance has joined with the Buzzards Bay Coalition's Baywatchers program to share Westport River water sampling data with local communities and the state. This volunteer water sampling program is one of the longest running in the state, and has provided DEP with a basis on which to determine water quality and measure impairments.
This collaboration performed most of the field work used to determine the TMDL, and advocated for resources needed to perform that work. Years of scientific assessment specific to the Westport River led to this TMDL calculation.