Neponset River Report Card: 2024
While ponds and the mainstem are doing well, Neponset tributaries still face threats from road runoff, sewer defects, and pet waste.
On August 23, 2024, NepRWA unveiled its Annual Water Quality Report Card, in coordination with the U.S. Environmental Protection Agency (EPA) and our partner watersheds, the Charles (CRWA) and Mystic (MyRWA). These grades represent bacteria levels throughout the watershed and how safe swimming and boating are on these waterbodies.
This year’s report card reveals that the biggest challenge in the Neponset is polluted rain runoff from streets, parking lots, and yards, as well as sewer system defects in a few isolated locations.
The report card shows the results of the last 3 years of water samples taken through NepRWA’s Community Water Monitoring Network (CWMN), our partnership with X-Cel Conservation Corp, and Estuary data collected by the Massachusetts Water Resources Authority (MWRA). Water samples were collected between May and October from 2021-2023, and represent how often the water is safe for swimming and boating from a bacteria perspective.
Most monitored ponds in the Neponset Watershed earned an “A,” and the mainstem of the River, where most recreation occurs, got “A” and “B” grades. This means that these sites were generally safe for swimming and boating, at least in terms of bacteria concerns (scroll down to learn more about what A, B, C, D, and F mean.)
In addition to bacteria, NepRWA also tracks dissolved oxygen and phosphorus, which are important for fish, wildlife, and recreation.
The grades in the Neponset are slightly better than in previous years (See 2022 Report Card). The past several years in the Neponset have alternated between drought (2020 and 2022) and rainy years (2021 and 2023).
The biggest challenge in the Neponset is polluted rain runoff from streets, parking lots, and yards. When it is raining, grades drop by 22% on average, nearly two full letter grades.
If you have any questions about the Water Quality Report Card, please contact NepRWA River Restoration Director, Sean McCanty at mccanty@neponset.org.
Water Quality Trends
NepRWA has been compiling report cards on the Watershed since 2020, which allows us to see how sites have changed in the last four years.
The site that has dropped the most in compliance is Traphole Brook in Norwood, which has gone from a “B” to a “D” in only 4 years, likely due to increases in road runoff through the highly impervious Norwood Automile and surrounding areas.
In contrast, Mother Brook in Dedham/Hyde Park has improved from a “C” to almost an “A” in the same period, likely because of stormwater improvements, including the closure of a transfer station that was discharging into the Brook.
The graph below shows how sites have changed from the 2020-2021 Report Card to this year’s 2023-2024 Report Card.
Sites are graphed from those that have fallen the most to those that have improved the most, with red outlines showing the loss since 2020-2021 and blue showing the gain since 2020-2021.
What’s in a Grade?
The report card grades are based on Massachusetts standards for swimmable water and a less stringent criteria for boating, defined by all 3 of the Boston Harbor watershed associations.
In freshwater, E. coli is used to determine suitability for recreation, while in the salt or brackish waters of the estuary, Enterococcus species are used. All NepRWA collected data relies on E. coli concentrations, while MWRA data uses Enterococcus.
The grades reflect the number of sampling events that either met boating standards (50% compliance) or both swimming and boating standards (100% compliance) over the last 3 years.
While useful, we caution that compliance scores can only tell you how often the standards are met on average and cannot replace your own good judgment about the safety of recreation.
In general, we recommend avoiding water-based recreation, especially swimming, directly following rainy days, as E. coli levels typically spike then.
The multiple factors that affect water quality and the bacteria “grade” of the Neponset River include:
- Stormwater runoff occurs during rain events and washes contaminants such as dog waste into streams and ponds via storm drain systems.
- Leaking sewer pipes or sanitary sewer overflows, which allow raw sewage to flow into streams and ponds.
- Poorly maintained septic systems, which allow bacteria and chemicals to flow from groundwater into streams and ponds.
Partnerships Make a Difference!
NepRWA relies on volunteers and municipal partnerships to help fulfill our mission to clean up and protect the Neponset River, its tributaries, and surrounding watershed lands.
Our Community Water Monitoring Network (CWMN) involves the help of dozens of dedicated volunteers, who take water samples from May through October from 41 sites across the Neponset River Watershed.
The water quality data gathered from the volunteer samples provides valuable insight into the health of the River and helps to identify where we need to focus remediation efforts.
Additional data is collected by X-Cel Conservation Corp with NepRWA staff and MWRA routine sampling in the Neponset Estuary. MWRA also provides bacteria and nutrient laboratory analysis for the CWMN program.
Our Neponset Stormwater Partnership (NSP) is a regional program that aims to reduce the cost and increase the effectiveness of municipal stormwater management programs through regional cooperation and resource sharing. Partners include the towns of Canton, Dedham, Foxborough, Medfield, Milton, Norwood, Quincy, Randolph, Sharon, Stoughton, and Westwood, along with the Metropolitan Area Planning Council (MAPC).
Residents and business owners can take the following steps to reduce polluted rain runoff:
- Always pick up after their dog and throw the waste into a trash can.
- Reduce the use of lawn chemicals.
- Build a rain garden that naturally filters pollutants.
- Redirect downspouts toward the lawn, garden, and shrubs.
- Clean up spills, like fertilizer, pesticides, and motor oil, from driveways and sidewalks.
- Wash cars on the lawn so that water filters into the grass.
- Use pervious materials when building walkways, patios, or driveways.
- Install a rain barrel to capture roof runoff.
Learn more at yourcleanwater.org/residents
If you spot pollution in a waterway or see any dumping, please email stormwater@neponset.org or give us a call at 781-575-0354 x 300.
