Water quality report card gives A- for the Charles River in Waltham

The 2024 Charles River Report Card gave the portion of the watershed located in Waltham an A-, with the overall river receiving a B-. 

The marks come from the Charles River Watershed Association.

The CRWA used water samples collected by volunteers to determine the water quality grades for the entire watershed, which includes the Charles, Mystic and Neponset rivers. It calculated the grades based on E. coli bacteria levels, cyanobacteria blooms and sewer overflow percentages in the water.

The lower watershed, which runs through Waltham as well as Newton, Wellesley, Weston and Watertown, was reported as having a water quality rating of “good” with room for improvement. The report cited “significant areas of impervious ground cover from increasing development and aging stormwater infrastructure” as issues facing that portion of the Charles.

Area residents can check CRWA’s flagging program webpage for information about day-to-day water quality. They can also look for physical flags located at boathouses along the river, with blue flags indicating good water quality that’s safe for recreation and red flags indicating poor water quality and safety concerns.

Betty Mackenzie, a volunteer steward with the Waltham Land Trust, is involved with cyanobacteria testing around the city. Mackenzie explained in an email to The Waltham Times that bad water quality is harmful not only to animals in the water but land-dwelling organisms as well.

“The toxins also cause problems for birds, animals and people, from skin and respiratory problems to liver and neurological issues,” Mackenzie said.

Mark Jacobson, vice president of local boat and paddleboard rental company Paddle Boston, says that CRWA’s water quality testing program is important for recreational use of the river. The company uses information from the flagging program and the Massachusetts Department of Health to help customers make informed decisions about going out on the water.

“I think more people are comfortable going out on the Charles when they have confidence in the water quality,” Jacobson said in an email to The Waltham Times. “The testing program both informs people when they may want to avoid being on the river and gives people confidence to go out at other times.”