Cape Cod residents, scientists note declining water quality

MASHPEE, Mass. — Paula Peters, Mashpee resident and member of the Mashpee Wampanoag Tribe, remembers her father taking her in a rowboat across Shoestring Bay to collect crabs when she was a child.

"I remember being able to look through the water and see them there," she said. "I was 5 or 6 years old."

Now, she says, the bay is completely dark. Brian Howe, professor of marine science and technology at the University of Massachusetts Dartmouth, said the water quality in Popponesset Bay, which contains Shoestring Bay, and Waquoit Bay in 2017 and 2016 was significantly worse than in all previous years of monitoring.

"Usually I try to find the positive in things, but this year, unfortunately, there's not that much positive," Howe said July 9 in a presentation to the Board of Selectmen.

Howe attributed the waterways' poor water quality to a very large phytoplankton bloom. These algae blooms, while not deemed harmful by themselves, choke the oxygen out of the water, killing various flora and fauna.

Since sampling began in 1997, the two bays have not met the state's water quality standards, Howe said.

"The real problem is habitat degradation," Howe said. "We lose eelgrass, shellfish, birds, we lose just everything. It's a whole-scale habitat decline."

To combat the ailing water quality, the town has put together a watershed nitrogen management plan that is projected to save taxpayers $190 million, according to some estimates, which is the cost saved by replacing sewers and wastewater treatment with shellfish. The plan looks to weigh the "most appropriate, cost-effective and politically feasible means" of tackling the nitrogen overload problem, according to the town's website. Town officials have put forward a shellfishing propagation program as part of the plan.

Officials look to grow about 10 million quahogs in waters off Popponesset Bay and Waquoit Bay this year - an increase of 2 million over the number cultivated last year - in an effort to restore water quality to state standards and restore shellfish beds to historical levels, according to Richard York, director of Mashpee's Department of Natural Resources.

York said the primary trouble with the bays stems from the amount of nitrogen, which is a product of runoff from individual septic systems, among other things. Shellfish consume nitrogen by feeding on the plants that depend on nitrogen.

It's still early, but the shellfish seeding program has shown some promise, York said.

"Some areas are getting better, and those are the areas where we are growing shellfish," he said.

Even the freshwater bodies are experiencing trouble. The Mashpee Health Department earlier this month issued an advisory about a thick blue-green algae bloom in Santuit Pond. Whereas blooms in the saltwater bays are a product of too much nitrogen, York said the bloom in Santuit Pond is a result of phosphorous leaching from the mud at the bottom of the pond.

The bloom in Santuit Pond is not harmful, but it has the potential to become toxic. York said the state Department of Public Health has monitored the blooms in the pond for years.

While the bloom does not rise to toxic levels, officials are suggesting people avoid swimming in the lake and to keep pets away. The toxin created by a blue-green algae bloom is a neurotoxin, according to Mashpee Health Agent Glen Harrington.

"It's known to kill cattle if they ingest large amounts of the water," Harrington said.

Without a formal vote, the selectmen agreed July 9 to put together a finance plan to bring to taxpayers at the October town meeting about the overall issue of water quality.

"The evidence is pretty clear there's something we need to do," Selectman Andrew Gottlieb said.

Associated Press