New grading system for MA watershed to provide more locally-specific analysis

The EPA, in coordination with the Mystic River Watershed Association, is utilizing an enhanced, more locally-specific analysis of water quality in Massachusetts's Mystic River Watershed to illuminate environmental conditions for the public.

July 20, 2015 -- The Environmental Protection Agency (EPA), in coordination with the Mystic River Watershed Association (MyRWA), is utilizing an enhanced, more locally-specific analysis of water quality in Massachusetts's Mystic River Watershed to illuminate environmental conditions for the public. Instead of one grade for the entire watershed, both organizations are issuing grades for each segment, totaling 14 separate stretches of river and its tributaries.

The grades are based on bacterial contamination found in analyzed samples that were collected by MyRWA volunteers over the past year at 15 monitoring sites throughout the entire watershed, as well as data collected at numerous locations by the Massachusetts Water Resources Authority (MWRA).

While an overall grade was created in 2006 to track water quality progress in the Mystic River Watershed, the amount of data now collected each year supports an improved and more sophisticated grading system, where a grade can be assigned, using similar criteria as in the past, to each major segment or tributary in the watershed.

Analysis of the data has brought to light the fact that water quality in the main stem of the Mystic River, including the Upper and Lower Mystic Lakes, is quite good on a regular basis. On the other hand, water quality in many of the urban tributary streams in the watershed is poor. Water quality in the main stem of the river from the Mystic Lakes, through Medford Square to Boston Harbor, meets water quality standards nearly all of the time, especially in dry weather.

However, water quality in many of the tributary streams feeding the Mystic often does not meet water quality standards. Water quality is frequently poor due to bacterial contamination in tributary streams such as Winn's Brook, Little River, Mill Brook, the Malden River, the Island End River, and Mill Creek, even in dry weather.

A second change to the grading system is that a three-year rolling average will now be used to calculate the grade for each segment. A grade for each year is calculated in the same manner as in the past; however, the current year's grade is averaged with the prior two years to produce the "rolling" three-year average. Such a system allows for a more complete and accurate assessment of recent water quality and is designed to better address climate variability from year to year, while allowing for real data trends to be more easily discerned.

Throughout the past year, there were continued efforts to improve water quality conditions in the Mystic River watershed. Both EPA and the Massachusetts Department of Environmental Protection (MassDEP) continue to pursue a number of active enforcement actions targeted at improving water quality throughout the watershed. These efforts have resulted in the removal of over 31,000 gallons per day of sewage from storm drains (nearly double the volume reported last year).

Numerous additional illicit connections have been identified and are scheduled to be removed this year. A number of additional repairs have been made that have prevented tens of thousands of gallons of sewage from discharging to the river during rain events. These aggressive efforts continue to address violations of water quality with regard to bacteria.

In a separate effort from the report card for bacteria, EPA recently launched a Mystic River water quality monitoring buoy in front of the Blessing of the Bay Boathouse in the city of Somerville. This buoy measures a number of water quality parameters such as temperature, dissolved oxygen, pH, turbidity, specific conductance, and chlorophyll that can be viewed by the public in near real time. The data will be available on EPA's Mystic River Website. In addition to providing real-time water quality data to the public, the buoy will also be used to monitor for and track cyanobacteria (blue-green algae) blooms.

See also:

"EPA seeking public input on phosphorus reduction targets for Lake Erie algal blooms"

"The Blue-Green Monster: How Harmful Algal Blooms Are Increasing Costs, Risks for WTPs"


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