Summer fish kill highlights Cranberry Bog water rights

by Karina Coombs

07a DeadFish
Dead fish line the shore in a pond in Chelmsford, near Carlisle’s Cranberry Bog. (Photo by Philip Stanway)

The heat of summer and abnormally low water conditions are thought to be the cause of a large fish kill in the waters in Chelmsford that feed into the Carlisle Cranberry Bog. The fish kill was first reported by Philip Stanway, founder of the Chelmsford Open Space Stewardship. “The clock was ticking,” said Stanway who had been watching the fish pool in very shallow waters in the weeks leading up to the event. “Fish were caught in one of the worst [affected] places in town.”

Letting nature take its course

Stanway—who started the Chelmsford Open Space Stewardship ten years ago—regularly walks the site and noted that he had not seen a fish kill of this size before. He found large numbers of Bass, Pike and Sunfish and puts the number of dead fish in the thousands. According to Stanway, Chelmsford Health Director Richard Day has advised visitors and their pets to avoid the area until the situation resolves itself.

Carlisle Conservation Administrator Sylvia Willard noted that there have been fish kills in the past, particularly during August when temperatures rise and water levels lower. “The fish have a hard time,” said Willard, explaining that they suffer from a lack of oxygen in the water. “[It’s been an] awful year in terms of rain.” 

Drought and beavers lower water levels

With the summer’s lack of regular rainfall, the United States Drought Monitor has determined that extreme drought conditions exist within parts of Middlesex County, a status not typical of this area. Many neighboring towns with public water supplies have water restrictions in effect. 

A beaver dam in Westford, which is contributing to historically low water levels at Chelmsford’s Heart Pond, may also be exacerbating the water conditions that led to the fish kill in the cranberry bog according to both Willard and Stanway. Carlisle has water rights for Heart Pond, which is used to irrigate the cranberries farmed by Mark Duffy. Duffy has said that the fall harvest will be his last. (See article, page 1 and “Carlisle-Chelmsford subcommittee confer on Cranberry Bog.” June 22.)

Communities connected by water

Three communities and a dizzying number of town boards and representatives are connected by the water that feeds and passes through the cranberry bog and the roughly 310 acres of associated conservation lands. Westford’s Pond Brook feeds into Chelmsford’s Heart Pond (a public swimming area as well as a water storage area for Duffy), which feeds into two ponds within the bog connecting Chelmsford and Carlisle and the active cranberry bog, while also passing through Great Brook Farm State Park and eventually into Chelmsford’s Russell Mill Pond, which Stanway notes is also low. “Water travels,” explained Stanway. “One town bleeds into the next.”

Because of the beaver dam at Pond Brook—the major water source for Heart Pond—Stanway reported that the water levels at the pond are at a 60-year low. Earlier this summer, the Heart Pond Association, a non-profit organization that supports, maintains and preserves the pond, filed a ten-day emergency permit request to the Westford Board of Health. The association proposed the installation of a pipe or “beaver deceiver” under the dam that would allow water to pass into to the pond and raise its levels so there would be enough stored water for this year’s cranberry harvest. The project was to be financed by the association. However, Westford Director of Environmental Services Jeffrey Stevens denied the permit request. ∆