Blue Flags Signal Safe Charles River Boating

By Stephen Brophy

Fenway News Online, Tuesday, July 6, 2010

Blue skies mean blue flags and good water quality for the thousands of people who will take to the Charles River over the long holiday weekend.  Since 1998, boaters on the river have been notified of the river’s health on a daily basis by Charles River Watershed Association’s (CRWA) Public Notification Flagging Program.  Boaters and the general public should look for CRWA’s flags along the river as they enjoy Boston’s 4th of July festivities!  With the current weather forecast for blue skies, the water quality forecast will likely call for blue flags.

Blue flags fly on days when there is a low probability of the river exceeding the State boating standard for E. coli bacteria.  Red flags are raised when there is a high probability of the river exceeding the State boating standard; red flags let boaters know about the potential health risk of using the river that day.  Recently, CRWA added a yellow flag which is flown on days when there is not enough data available to make a determination that the river is safe, so boaters should use caution.  Results are relayed to nine boat houses or yacht clubs in Newton, Cambridge and Boston where flags are hoisted on a daily basis.  CRWA also notifies river-users of the daily flag color through their website (www.charlesriver.org), a water quality hotline (781.788-0007×301), a daily e-mail, and Twitter.

Kicking off its thirteenth season operating the Flagging Program, CRWA this week began notifying the public of the daily water quality forecast in the Charles River Basin, the nine-mile stretch of river from the Watertown Dam to the New Charles River Dam.  “This program has been key to raising the public’s awareness of the river’s improved health.” states CRWA’s Director of Projects, Kate Bowditch. “It also provides the local boating community with a valuable service, notifying river-users about the potential health risk associated with going out on the Charles on any given day.”

Red and yellow flags typically fly after rain storms when rainwater runoff washes bacterial pollution from leaking sewer pipes, animal waste, and other sources into the river.  Additionally, red and yellow flags can also indicate the presence of high cyanobacteria concentrations.  Cyanobacteria are photosynthetic algae that produce toxins which can potentially harm humans or animals that come in contact with the river water.  Some boaters choose to stay off the river on red and yellow flag days; others choose to use the river but take the recommended precaution of washing carefully after being on the river.

CRWA uses simple predictive models to forecast daily water quality conditions, similar to the manner in which weather is forecasted.  These models are based on the relationship of E. coli bacteria to a variety of environmental factors, including rainfall, river flow, temperature and wind.  The model predicts the probability of the river exceeding the State secondary contact recreation (i.e., boating and sailing) standard for E. colibacteria. CRWA also collects weekly bacteria samples to verify the accuracy of this model.

CRWA continues this program year after year because boaters on the Lower Basin need to know when the level of bacteria or cyanobacteria in the river poses a health risk so they can make an informed decision about their desired contact with the river.  Basin boathouses and clubs displaying flags include: Charles River Canoe and Kayak at Herter Park, Henderson Boathouse (Northeastern University), Newton Yacht Club, Riverside Boat Club, Union Boat Club (near the DCR Hatch Shell), Access Sport America at Spaulding Dock, Charles River Yacht Club, Community Rowing, and Weld Boathouse (Harvard University).

Funding for this project is provided by Boston Water and Sewer Commission.

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