Route 58 in Halifax, MA separates Monponsett Pond into two water bodies. East Monponsett Pond is picturesque and lovely. West Monponsett Pond not so much. In the summer, the gas-like stink emanating from the pond causes locals to call the fire department to make sure there aren’t any dangerous gas leaks.
According to Cathy Drinan, the local health agent, “It’s getting worse every summer. The odors are terrible… they cause headaches.” The smell is emitted by the blue-green algae blooms that smothers the pond every summer without fail.
East Monponsett Pond is connected to West Monponsett Pond by a culvert under the highway. Water flows through the culvert from east to west, which then flows out of Stump Brook. Drinking water is pumped from East Monponsett. During late summer and early fall when it’s dry, the pond is lowered even more, which can cause water to flow from west to east. Both state and local officials are actively working to make sure water from the west pond doesn’t contaminate the east.
The algal bloom problem isn’t new. A report published in 1987 blames errant septic systems for leaching polluting nutrients into the pond and fueling the algae blooms. Since then, on more than one occasion, there have been algal blooms with more than twice the cells per milliliter count needed to justify closing a lake (70,000). In fact, in 2013, West Monponsett Pond achieved the dubious record of longest consecutive beach closures in the history of Massachusetts.
In June of 2017, Halifax treated West Monponsett Pond with aluminum sulfate to bind to the phosphorus in the water that fuels algal blooms. Unfortunately, the soupy stink returned and the pond was closed in early August.
In addition to the treatment, the town has started looking into longer-term solutions, including managing stormwater and limiting runoff from nearby cranberry bogs. The town recently received a grant to prevent stormwater runoff and reduce other sources of excess nutrients in the ponds.
This May, the town again treated the pond with aluminum sulfate. Only time will tell if it prevents another harmful algal bloom.
This blog post was researched and written by Dorothy Cooperson Vieweg, ORI Summer Intern, with some assistance from others.