Region 1: EPA New England
Addressing Excessive Nutrients in the Charles River (TMDL)
EPA is implementing a targeted effort to apply more stringent controls on stormwater pollution in the Charles River watershed, where stormwater containing high levels of phosphorus is a chief culprit in dramatic algae blooms – including toxic cyanobacteria – that have plagued the river in recent years.
Phosphorus is responsible for the neon blue-green algae blooms that have in recent years plagued the river during warm summer months. Algae blooms threaten recreational use of the river and degrade fish habitat and aesthetics. EPA's goal is to reduce phosphorus discharges to the lower Charles by 54 percent to restore the river to a healthy state.
On November 17, 2008, EPA took action, under the “Residual Designation Authority” of the federal Clean Water Act (CWA), to require certain industrial, commercial and high-density residential facilities in the Massachusetts Towns of Milford, Franklin, and Bellingham to operate under a CWA permit for stormwater discharges. This requirement applies to facilities with two or more acres of impervious area (parking lots, roofs, roadways, etc.).
The new EPA requirements are being piloted in the three communities at the upstream end of the Charles – Milford, Franklin, and Bellingham. EPA will require these facilities to apply for a Clean Water Act permit for stormwater discharges which eventually reach the Charles River.
The permits will require that these facilities reduce phosphorus discharges by 65 percent through a variety of stormwater management practices. Ultimately, these requirements will likely apply to the entire Charles River watershed. These new steps will ensure that owners of large private facilities take responsibility for runoff from their sites.
Applying Best Management Practices to reduce stormwater from being discharged directly into rivers, streams or other waterways will also provide significant benefits to the “recharge” of groundwater sources.
Background – Establishing a TMDL for Phosphorus in the Charles River
In October 2007, EPA and the Massachusetts Dept. of Environmental Protection (MassDEP) announced aggressive targets to reduce harmful levels of the nutrient phosphorus from entering the Charles River through storm water. EPA and MassDEP established a "Total Maximum Daily Load" (TMDL) for discharges of phosphorus into the lower Charles River. A TMDL determines how much of a pollutant can be put into a body of water before it has harmful effects. EPA and MassDEP developed and approved the new limits on phosphorus to the lower Charles using extensive data collected in the river.
The TMDL forms the scientific basis for taking specific actions to ratchet down the release of phosphorus into the river. Phosphorus enters the river by a number of routes, some of which are already controlled by permits issued by EPA and MassDEP. These include combined sewer overflows, illicit connections through which sanitary sewage seeps into storm drains, and outflows from wastewater treatment plants. While all of these sources have come under stricter discharge limits in recent years, a major uncontrolled source of phosphorus is stormwater runoff - rainwater and snowmelt that carries contamination into the Charles.
With the TMDL establishing a more protective maximum load of phophorus, EPA and MassDEP are working with municipalities and other dischargers to reduce their contribution of phosphorus to the Charles. Techniques to reduce phosphorus in stormwater include the construction of infiltration chambers, the installation of permeable pavement that enhances the return of water to the soil, the use of high efficiency street sweepers, and other low-impact development methods.
The phosphorus-induced algae blooms contain "blue green" algae, actually a form of bacteria known as Cyanobacteria, whose cells may release a toxin when they die. Exposure to the toxin can cause skin rashes and irritate the nose, eyes or throat, and if ingested can lead to serious liver and nervous system damage. Other harmful affects of the algae include reduced water clarity, nuisance scum, and reduced oxygen in the water. Oxygen is necessary for a healthy fish habitat.