Algae Mats

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.

Cyanobacteria are fluorescent-green algae "that look an an awful lot like green snot in the water column," Mr. Gottlieb said. The growth of cyanobacteria is fueled by an excess of phosphorus washed into ponds from human sources such as septic systems, fertilizer use and road runoff.

The toxins produced by cyanobacteria have been known to kill pets and cause liver damage in humans.

The 93 ponds included in the study represent just 9 percent of Cape Cod's 996 freshwater ponds, a sample size that Mr. Gottlieb said is much too small for the public health and environmental threat posed by cyanobacteria.

"We need to play major and rapid catchup with our understanding of what is happening in the freshwater environments so we can take corrective action," he said. "Because of the toxicity associated with cyanobacteria there is a real public health reason to be concerned about the ponds that is not reflected in the embayment concerns."

Citing the results of the latest State of the Waters report, the APCC is calling on the Barnstable County government to undertake a region-wide 208 water quality study on the scale that was done in the past two decades to assess the extent of nutrient pollution in coastal embayments.

"We know enough now as a result of the 208 study and the individual towns nitrogen loading studies to know what we need to do with the embayments," Mr. Gottlieb said. "Now we're getting a fuller understanding of the degree to which our freshwater resources are suffering from that neglect."

The 208 studies conducted on each of Cape Cod's estuaries pinpointed nitrogen as the source of the degraded water quality and gave target levels of nitrogen, known as total maximum daily loads, that would have to be achieved to begin restoration.

The studies found that a lack of proper wastewater management results in nitrogen from septic systems washing through watersheds and into the saltwater embayments. Once in the embayments, the nitrogen fuels excessive algae growth that overwhelms the marine ecosystem.

Mats of algae and murky water prevent light from reaching the bottom of the bay, crowding out native species. When the algae dies, the decaying organic material can consume oxygen from the water, killing fish and shellfish.

Nitrogen pollution has long since decimated shellfish populations and eliminated the once-prolific beds of eelgrass on which the shellfish rely.

Some Cape Cod towns have forged major wastewater plans to reduce nitrogen inputs. But efforts to implement the plans have progressed slowly in most towns, with few towns having reached the point of laying sewer pipe in the ground.

"Frankly, we didn't expect any meaningful improvement in estuarine water quality because of the general slowness with which towns have started to deal with the issue," Mr. Gottlieb said.

Last year 33 of the 48 (69 percent) of the embayments included in the State of Waters report showed unacceptable water quality at at least one monitoring station. This year, that number increased to 38 of 48, or 79 percent.

(6) comments


We know for more than a decade of studies that our bays and ponds are polluted due to Septic and Storm Run off. We knew 30 years ago that exactly this would happen if we build out the Cape and did not address wastewater. It is not from the birds and seals. Yes it is from poorly regulated development where the industry has taken over the local regulators long ago and the state more recently. And yes it harms commercial fisherman as the estuaries are spawning grounds.


The Town of Falmouth Planning Board should do the right thing and remove the deed restrictions forcing about 300 home owners to have denite systems. The systems have proven to be a complete waste of resident's money, because 300 systems for 10,000 homes is nothing. Not only has the Town Planner and Planning Board been woefully inconsistent inconsistent with their decisions over the past 20 years, most developers have figured out that if they do a 40B the requirements don't apply. Besides, the Planning Board routinely overstepped its boundaries by requiring systems in areas where technically the bylaw does not apply, i.e., well beyond the sensitive areas.



It's the seals and geese and swans and fish pooping all over the place but not us sapiens....we b blameless.

Wellfleet John

It's interesting that these studies point to excess nitrogen only from fertilizer run off and inadequate septic systems affecting our ocean estuaries, puting the onerous only on humans. In the past 48 years, because of a hastily and ill conceived law, The Marine Mammal Protection Act has allowed the northwest Atlantic gray seal population to explode unchecked to more than 500,000, with at least 50,000 infesting our inshore waters and beaches of Cape Cod and the Islands. These seals weighing as much as 800 pounds consume 5% of their weight in fish daily or about a million pounds of fish that will never spawn a new generation. Their resultant mountain of mammalian feces ends up along our beaches, polluting our coastal habitat with excess nitrogen. Yet these same researchers are seriously making the argument that human sourced nitrogen is bad for our estuaries, but seal sourced nitrogen is good for our estuaries? Sound like a "load" to any thinking person.


And Don’t forget the geese; they are veritable pooping machines.


I agree John, additionally with the fish stock shrinking the fishing industry shrinks along with it. It's time to consider culling the seal population.

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