Two-thirds of coves, inlets and similar water bodies known as embayments, and one-third of ponds on the Cape, have unacceptably low water quality, according to a new report from the Association to Preserve Cape Cod (APCC).
The result in many cases is loss of ecological function, habitat, species diversity, and aesthetic value.
The problems are largely caused by poorly treated stormwater runoff, poor land use practices—like overuse of fertilizers—and most urgently, inadequately treated wastewater, according to the report.
Septic systems often allow excess nutrients like nitrogen to seep into the groundwater and end up in water bodies. Once there, these nutrients foster unhealthy plant growth and promote bacteria from algae blooms that can be toxic in certain concentrations.
In fact, the APPC found the worst water samples were from the southern and eastern coasts of the Cape in densely populated areas that rely on septic systems.
Andrew Gottlieb, executive director of the APCC, said these problems are only exacerbated by climate change.
“We're providing the nutrients through these external inputs and we're doing them in an environment that has a longer growing season and is warmer in the extremes than it has been,” Gottlieb said.
The APCC found that drinking water on the Cape is “excellent,” according to Consumer Confidence Reports, but there are emerging concerns about unregulated chemicals like pharmaceuticals, microplastics, endocrine-disrupting compounds, and substances called PFAs used in manufacturing that repel oil and water.
“We should be worried about the trends that are in place because the environmental impacts show up a little bit more readily than some of the public health impacts when it comes to the nutrients. But this is all one related system and an insult somewhere ultimately shows up everywhere,” Gottlieb said.
The APCC compiled data from institutions like the Center for Coastal Studies, UMass Dartmouth, individual pond associations, and the Environmental Protection Agency to complete its review.
In all, the APCC evaluated the water clarity, levels of chlorophyll, dissolved oxygen, and organic nitrogen in 150 freshwater ponds, 20 public water supply systems, and 50 embayments, which are ecologically rich areas where fresh and saltwater mix.
But, Gottlieb said, this regional overview isn’t enough.
“Only 15 percent of the ponds on the Cape have any sort of water quality data,” Gottlieb said. “As a result, we think that this report is probably underestimating the degradation of our freshwater systems as well as the marine environment.”
The APCC recommends individuals do their part by changing their land-use practices and reducing the amount of fertilizer on their lawns.
At the municipal level, towns can implement sewer systems and invest in other alternatives to septic systems, while finding better ways to treat stormwater runoff.
“Hopefully this report will serve as a wakeup call,” Gottlieb said. “Water is everything on Cape Cod. … If we don’t have water quality, we don’t have anything.”