Cape Cod’s water quality remains a top environmental problem, with significant worries about the health of coastal embayments and freshwater ponds. At the same time, the region’s public drinking water supplies continue to perform well.
Those are the findings of the newly released 2024 State of the Waters: Cape Cod report issued by the Association to Preserve Cape Cod, a non-profit environmental advocacy organization based in Dennis. This is the organization’s sixth year of evaluating the quality of the Cape’s coastal and inland water bodies, as well as its public drinking water supplies.
Association President Andrew Gottlieb said the Waquoit Bay system in Falmouth and the Popponesset Bay system in Mashpee and Barnstable “are probably the worst” on the Cape for what are called nutrient loads, the accumulation of nitrogen and phosphorus which lead to algae blooms, robbing the water of oxygen, killing plants and sealife.
In this Sept. 28, 2023 photo, environmental researcher Nicole Corbett, left, watches as Barnstable Clean Water Coalition field operations manager Luke Cadrin lowers a camera into Ockway Bay in Mashpee to take video of the shallow area. Corbett is able to see what the the camera is taking in real time on the screen she is holding. Corbett studied seaweed and jellyfish to get an understanding of the water quality in Cape Cod embayments and estuaries, especially Popponesset. The Association to Preserve Cape Cod has released its 2024 State of the Waters report which says water in the Cape’s bays and freshwater ponds are struggling because of nitrogen and phosphorus from septic tanks and other sources.
Inadequately treated wastewater from septic systems is the main source of nitrogen pouring into the Cape’s embayments from sources both upstream of and around them, though stormwater runoff and chemicals from fertilizers play a role.
The Association’s report uses data from local organizations, towns and other monitoring agencies to grade water quality. For coastal embayments and freshwater ponds, the grades are either “acceptable” or “unacceptable,” based on specific measures. For public water supplies, grades range from “excellent” to “poor,” based on compliance with state and federal standards.
Coastal embayments: Unacceptable quality continues
This year’s report identifies 43 coastal embayments — representing 90% of those evaluated — with “unacceptable” water quality stemming from heavy concentrations of nitrogen and phosphorus and other pollutants.
All embayments on Nantucket Sound, and most in Buzzards Bay, have ongoing unacceptable water quality. And although Cape Cod Bay has four embayments that still have acceptable water quality, the data collected from 226 monitoring stations around the Cape show that no embayments have shown significant improvement since 2019, and “the number of embayments with acceptable water quality has steadily declined.”
Gottlieb said the assessment is based on data from 2018 and 2022.
“We didn’t rescore the marine systems this year because, even though a lot of towns have made investment in wastewater treatment,” he said. “They’re not far enough along in implementation to actually reduce the load, so the systems that are bad stay bad.”
This pond adjacent to Miss Thachers Pond in Yarmouth Port shows how chemicals from the septic systems of neighboring homes are harming the water. Photo taken Aug. 31, 2022.
Freshwater ponds: Limited data, ongoing decline
The Cape’s freshwater ponds face similar challenges. The report reveals that 28% of the 138 ponds graded in 2024 have unacceptable water quality — a figure that has remained fairly steady over the past six years. While the percentage of ponds with acceptable water quality showed a slight increase in 2024, their overall health remains a concern.
One of the challenges with assessing the region’s 890 freshwater ponds is the lack of sufficient water quality data — only 16% are included in the report. Ponds were graded based on the APCC’s cyanobacteria monitoring program and the Carlson Trophic Index, which evaluates total phosphorus, chlorophyll and water clarity.
No town on Cape has a comprehensive plan to handle problems with freshwater ponds. The APCC is calling for a greater commitment to monitoring and restoring ponds.
Towns have begun the trying to reduce nutrient loading into marine systems and are “headed in the right direction” but ponds remain “the neglected stepchild of the water quality situation. The data shows that our ponds are suffering,” Gottlieb said.
This device is used to check the water quality in Shubael Pond by Barnstable Clean Water Coalition. Photo from October 2021.
Public water supplies: A bright spot
The Association’s report found that public drinking water supplies remain in strong shape — 19 of 21 public water supplies received an “excellent” grade for water quality, meeting all state and federal standards, and two received a “good” grade owing to minor detections of total coliform bacteria that were corrected.
The 2024 report also highlights the ongoing issue of per- and polyfluoroalkyl substances, or PFAS, a group of man-made chemicals that have been found in the groundwater of some Cape Cod wells.
While no public water supplies exceeded the state standard for PFAS6 in 2024, 11 of the 21 water supplies detected some level of PFAS, according to the APCC’s findings. Even though these did not exceed the state limit, Gottlieb said the presence of PFAS is troubling and calls for continued monitoring and planning for future treatment.
Moving forward: Immediate actions and long-term solutions
Gottlieb called the continued water quality problems “depressing,” but not hopeless since the state and towns are trying fix them.
“It’s a lot less depressing that it was five years ago,” he conceded. “The downside is we’ve really punished these systems over the years. The good news is the fix is not rocket science — it’s just reducing the load from underperforming septic systems.”
Although it will take time, Gottlieb said, “evidence from other places shows that it can be done.” He gave Boston Harbor as an example — a water body that was considered the dirtiest harbor in the country in the 1980s that is now “relatively clean” as a result of wastewater treatment improvements that went into effect in the 1990s.
What’s needed on the Cape, he said, is sustained momentum on improving water quality through wastewater management projects in tandem with conservation projects. As towns implement projects, it’s expected that signs of recovery will show in the data that form the Association’s annual water quality report.
To review the 2024 State of the Waters: Cape Cod report, visit capecodwaters.org
Heather McCarron writes about climate change, environment, energy, science and the natural world, in addition to news and features in Barnstable and Brewster. Reach her at hmccarron@capecodonline.com.
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This article originally appeared on Cape Cod Times: Cape Cod water quality report: Drinking water scores, freshwater ponds
