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APCC: Cape Cod Water Quality Is on the Decline

 The Association to Preserve Cape Cod (APCC) has released its second annual State of the Waters report this week, and found an increase from last year in the percentage of saltwater embayments and ponds with unacceptable water quality. 

The report found that of 93 ponds studied, 42 percent had unacceptable water quality, and the percentage of acceptable ponds decreased from 61 percent in 2019 to 58 percent in 2020. 


“Once again, the data shows clearly that nutrients are the single biggest driver of poor water quality on Cape Cod,” Gottlieb said in a press release. “The greatest source of nutrients impacting embayments and ponds is from inadequately treated wastewater from septic systems. Stormwater runoff and fertilizers are additional sources of nutrients impacting the Cape’s waterbodies." 


Some of the ponds with poor water quality were also covered with potentially toxic cyanobacteria blooms, that can make the water look like a dense, green pea soup and pose major threats to public health. 


“We have known for years about the degraded quality of our bays, but the impact of nutrients on the Cape’s freshwater ponds, and the severity of the public health threat of toxic cyanobacteria blooms supported by excess nutrients, is a new and disturbing finding,” Gottlieb said.  

Ponds were graded using water quality data from no earlier than 2015. That’s because for many ponds the most recent water samples are five or more years old, making it remarkably difficult for researches to assess the overall health and safety of the nearly 1,000 ponds on the Cape. 


“We have strong reason to believe that ponds are actually more impacted than even this report reveals because lack of data prevents further assessment of more ponds,” Gottlieb said. 

Still, the quality of public drinking water supplies in 2020 was deemed excellent for the second year in a row. 


“Grades were determined by using the publicly available Consumer Confidence Reports for 2019, with the scoring based on whether water quality meets existing state and federal drinking water standards,” according to the news release. “All 20 of the public water supplies in the 15 towns across the Cape received a score of excellent.” Researchers did not include per- and polyfluoroalkyl substances, or “forever-chemicals” better known as PFAS, in their analysis.  


Of 48 coastal embayments studied, 79 percent had unacceptable water quality, representing a 11 percent increase from last year. APCC executive director Andrew Gottlieb warned embayments with poor water quality are not only an eyesore, but could have ecological impacts. 


“So if the resource is impaired it doesn’t provide a habitat that would support our traditional shellfisheries,” he said. “So therefore you’re not able to go out there and find…  naturally occurring oysters, quahogs, scallops, or blue crabs.”


APCC is now calling for the Cape Cod Commission to launch a region-wide water quality study on ponds, which can be used to develop a more robust regional water quality monitoring program. Until then, Gottlieb said he hopes towns and homeowners will reduce their nutrient loads by limiting fertilizer use, managing stormwater runoff, and prioritizing sewer infrastructure. 


The ultimate goal, he said, is to understand, triage, and remediate water quality in ponds before the problem grows more apparent and more urgent. 

Eve Zuckoff covers the environment and human impacts of climate change for CAI.