Mats of algae, a sign of nutrient pollution, cloaked the surface of the Mashpee River this past June.
Nutrient pollution has long degraded Cape Cod’s bays and estuaries, but data analyzed by the Association to Preserve Cape Cod suggests the Cape’s freshwater ponds also might be nearing a state of crisis.
In the second annual “State of the Waters” report released on Monday, October 26, the APCC, an environmental nonprofit group, determined that 38 of 48 saltwater embayments had “unacceptable” water quality—an increase from last year’s numbers.
Meanwhile, 39 of 93 ponds graded had “unacceptable” water quality.
“The disappointing finding related to ponds is that the more we look the more we see conditions that are unacceptable,” said Andrew R. Gottlieb, executive director of the APCC.
About 40 percent of the ponds sampled had levels of cyanobacteria—a potentially toxic algae—that were high enough to warrant public health advisories and the closure of the ponds to recreation.