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Region 1: EPA New England

2012 Mystic River Watershed Report Card
Frequently Asked Questions


What is the grade for the 2012 calendar year?

The grade for the 2012 calendar year is a "D."  Based on bacterial water quality standards, during the 2012 calendar year, waters were safe for swimming 47% of the time and safe for boating 75% of the time. EPA's Annual Report Card grade is based upon water quality data provided by the Mystic River Watershed Association's baseline monitoring program. Each month, a group of trained volunteers in the Mystic Monitoring Network (MMN) gather water quality samples from fifteen representative sites throughout the watershed. These samples are sent to a laboratory and analyzed for bacteria, nutrients and other valuable indicators. MyRWA staff assesses the data for quality assurance and make the information available to any interested party. The annual grade is a measure of how frequently bacteria levels in these samples meet the state water quality standards for boating and swimming. The state has set specific benchmarks of 235 and 1260 E. coli per 100 ml of water as acceptable levels for swimming and boating respectively.

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Why was the grade a D for the 2012 calendar year?

The easiest way to understand the grade is to start with a short description of how the grade is calculated. An algorithm calculates the percentage of days during dry and wet weather that bacteria levels at each of the fifteen sampling sites meet MassDEP water quality standards for swimming and boating. EPA then uses an average between the overall percentages that water quality met criteria for swimming and boating (for 2012, it is 61%) as well as a set of qualitative criteria described below:

A –- meets swimming and boating standards nearly all of the time
B -- meets swimming and boating standards most of the time
C -- meets swimming standards some of the time, and boating standards most of the time
D -- meets swimming and boating standards some of the time
F -- fails swimming and boating standards most of the time

Overall water quality scored a lower average than the 2011 calendar year.  In particular, wet weather water quality was poor.  Wet weather water quality can be directly affected by both the amount of precipitation and the manner in which it occurs.  The 2012 calendar year had numerous thunderstorms over the summer, and sudden, heavy precipitation can cause more pollutants to be carried into receiving waters.  While improving dry-weather water quality is a focus of EPA's efforts, EPA is also issuing new stormwater permits aimed at improving both dry and wet-weather water quality.

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If it rains a lot will the grade be worse?

Because the Mystic Monitoring Network (MMN) samples once per month regardless of the weather, we cannot predict how many samples will be taken in dry or wet weather each year.  To calculate the grade, EPA normalizes the data to control for wet weather by giving dry weather sample results more weight in the overall grade (75% dry weather/25% wet weather).  These percentages are based upon weather conditions seen during the first year EPA calculated a report card for the Mystic River Watershed and by normalizing in this way we are able to standardize the grade for year-to-year comparison.  It is true that the water quality is impaired more frequently during wet weather conditions than dry conditions.  If our calculations did not control for the frequency of wet and dry weather, we would see greater variability in the grade on a yearly basis that would mask any trends in water quality.

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Why was water quality in the Mystic River Watershed poor during the 2012 calendar year?

Water quality for the 2012 calendar year decreased slightly in dry weather and more so in wet weather compared to past years.  Water quality is directly affected by stormwater runoff, illicit connections and the Combined Sewer Overflows (CSOs) and Sanitary Sewer Overflows (SSOs) that occur during large precipitation events.  Monthly data continues to highlight a number of locations in the watershed with poor water quality in both wet and dry weather.  Known or suspected illicit discharges are actively being investigated in these areas.  EPA continues to work with MyRWA, municipalities and the state to further analyze the data and take appropriate actions where necessary.  While investigative work to date has identified a number of causes of poor water quality, further investigation and the design and construction of remedial measures takes time (months to years) before improvements in the receiving waters can be documented.

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Who collects water quality samples?

Water quality samples are collected by the Mystic Monitoring Network (MMN) that is organized by the Mystic River Watershed Association.  The MMN is a volunteer-based project made up of trained citizen volunteers, student interns, and scientific advisors throughout the Mystic River Watershed. The goals of the MMN are to establish a high quality baseline of data for the Mystic River Watershed, identify and address water pollution problems, raise public, municipal and state agency awareness of water quality in the Mystic, and create a network of informed and active citizen advocates.  The MMN has been collecting water quality samples since 2000.

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What is being done to improve water quality in the Mystic River Watershed?

EPA is in the process of issuing a new draft general stormwater permit that will apply to many municipalities throughout Massachusetts.  This general permit will make a significant improvement in how stormwater is handled and discharged to receiving waters, and is designed to make significant improvements in stormwater water quality throughout the state.   In addition, municipalities throughout the watershed are examining their stormwater systems and related discharges for areas to make improvements.  These communities are working to upgrade aging infrastructure and reduce the flow of sewage into surface water bodies. 

In the Alewife area, the Massachusetts Water Resources Authority ("MWRA") and the City of Cambridge are nearing completion of a large constructed wetland/park/detention basin as part of the EPA-approved Boston Harbor Long Term Control Plan ("LTCP") that will allow for a significant reduction in the CSO volume discharged to the Alewife Brook.  Many of the remedial projects required by the LTCP are nearing completion, including several that will improve water quality in the Mystic watershed.

At the same time, the science and water quality subcommittees under the Mystic River Watershed Initiative Steering Committee are working to improve water quality in the Mystic River Watershed.  The science subcommittee  coordinates water monitoring needs, while the water quality working group has identified specific priorities and actions they would like to collaboratively tackle over the coming two years including reducing SSOs, offering technical assistance to municipalities, reducing nutrient loading, and remediating legacy pollution.    

Finally, EPA and MassDEP have issued enforcement orders to several municipalities in the Mystic River Watershed requiring them to identify and remediate SSOs and illicit connections that discharge raw sewage to the watershed.  So far, these actions have removed in excess of 14,000 gallons per day of sewage from storm drains discharging to the Mystic River (that is over 5.1million gallons per year).  A number of identified illicit connections are being repaired right now, and EPA anticipates a continued increase in the volume of sewage removed from the watershed over the next several years.  Additional investigations will continue and EPA and MassDEP will take any appropriate actions as new data and information become available. 

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Why don't you use other parameters besides bacteria?

The Mystic River Watershed grade was developed to easily communicate how frequently water quality meets criteria that are acceptable for recreation (e.g. swimming and boating). There has been a lot of research done to identify a relationship between high bacteria levels and public health risk of illness during recreation in contaminated waters. While other parameters are important for the health of the ecosystem (e.g. nutrients, TSS) they are not as easily correlated with human health. The Mystic River Watershed grade provides a snapshot of one aspect of water quality.

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What is the difference between the Mystic River Report Card grade and a similar grade issued for the Charles River?

Unlike the grade determination for the lower Charles, when assessing water quality to assign a grade to the Mystic River Watershed, EPA uses an average between the overall percentages that water quality met the state criteria for swimming and boating (for 2012, it is 61%) as well as qualitative criteria that are similar to those developed for the Charles River Initiative, as follows:

A -– meet swimming and boating standards nearly all of the time
B -- meet swimming and boating standards most of the time
C -- meet swimming standards some of the time, and boating standards most of the time
D -- meet swimming and boating standards some of the time
F -- fail swimming and boating standards most of the time

Other differences between the grades include the locations where water quality samples are taken.  In the lower Charles, monitoring samples are collected in the middle of the river's main stem from the Watertown dam to the New Charles River dam in Boston, whereas in the Mystic River Watershed, samples are taken throughout the entire watershed and often in the tributaries before they discharge into the main stem of the river. These different methods represent long-established sampling locations and monitoring efforts used by the two watershed associations. The watershed-wide approach in the Mystic is different than the approach EPA began using in the lower Charles in 1995 and allows EPA and other stakeholders to better identify "hot spots" as well as better understand water quality problems in the tributaries. For these reasons, as well as the use of numerical averaging in the Mystic River Watershed, it is important to note that the grades cannot and should not be compared.  However, these grades do provide a basis to track annual progress and water quality within each watershed.

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What sections of the Mystic Watershed are better than others?

Water quality in the main stem of the Mystic River between the Route 16 bridge and the confluence with the Inner Boston Harbor is quite good.  Significant settling of pollutants can occur where the river widens and flow slows down, and this is generally reflected in the data collected in this area of the watershed.  This is similar to what happens upstream in the Upper and Lower Mystic Lakes and in the Charles River basin to the south.

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