Crackrock Pond Foxborough

The Kerr-Carpenter-Haigis house marker

While volunteers with the Neponset River Watershed Association have found bacterial levels in Crack Rock Pond make it safe for swimming, it’s unlikely that anyone is clamoring to take a dip from its North Street shores.

E. coli concentrations in the pond in 2018 were less than half of the level determined safe for swimming, the association said in a press release.

But its unappealing neon green color and awful smell, thanks to a algae bloom that endangers the wildlife, keeps swimmers at bay.

“Excessive amounts of phosphorus, a key fertilizer for plants, is driving the impressive blooms, and foul smells coming from Crackrock Pond,” said Chris Hirsch, an environmental scientist with the Neponset River Watershed Association, which has been monitoring the water quality in the pond for more than 20 years.

According to the association’s recently published report, on the water quality of Crackrock Pond, phosphorus levels were almost ten times the level EPA considers healthy for ponds.

“The pond’s high phosphorus level is not only causing ugly blooms, but it’s also depleting the supply of oxygen in the water, which aquatic animals depend on to breathe,” Hirsch said.

The association’s report says the high concentration of phosphorus is likely the legacy of past discharges upstream in the Neponset River. However, there are concerns that landscaping runoff, which includes fertilizer, is also contributing to the problem.

“Our results also suggest that stormwater runoff from the nearby landscape is contributing to the problem,” said Ian Cooke, the association’s executive director. “Something will need to be done to remove or sequester the phosphorus that is cycling within the pond, but preventing new stormwater inputs of phosphorus is a major piece of the restoration puzzle. Preventing stormwater pollution is critical to protecting other ponds and waterways in Foxboro from a similar fate.”

Town officials and the association have been working together, along with neighboring communities through the Neponset Stormwater Partnership to comply with new requirements from the Environmental Protection Agency to reduce polluted stormwater runoff.

Under the new requirements, the must implement pollution reduction measures, such as more frequent street sweeping, new rules for land developers, and checking for and eliminating sewer and septic leaks. Educating the public about stormwater pollution is another requirement.

“The new permit requirements are a significant new obligation for our small department, but we are making progress and the outcome of our efforts will benefit all residents in Foxboro,” said Town Engineer Chris Gallagher.

For the full report on Crackrock Pond, and for more information about to prevent phosphorus runoff, visit