Harmful Algae Blooms Threaten Massachusetts Ponds and Estuaries

Septic tanks releasing excess Nitrogen and Phosphorous are causing algae blooms, damaging the aquatic vegetation and wildlife in MA.

Photo Credit: Massachusetts Department of Public Health

Photo Credit: Massachusetts Department of Public Health

Of all the ponds and tournaments I’ve fished over the last 20 years, there is one season I look forward to every year. In April and May the herring start to migrate to their freshwater spawning grounds, flooding Cape ponds with an abundance of feed for large and smallmouth bass.  When you’re on the water and see the frenzied activity of spawning herring on the shoreline, tie on a jerk bait and hold on.  Catching 5+ pound smallmouth bass with herring tails visible in their mouths is something that never gets old.

But there is a looming threat to our fisheries – the presence of excess nitrogen (N) and phosphorus (P). From a freshwater perspective, ponds such as Billington Sea, Santuit Pond, and others are routinely closed for recreational activities from harmful algae blooms.  If you have seen a pond, that looks “pea-soup” green, this is from a bloom of cyanobacteria.  It can be toxic to humans and animals if ingested.  While shallower ponds are more susceptible to this sort of bloom, in 2020, larger bodies of water were closed because of this, such as Great Herring Pond in Bourne and several others on Cape Cod.

For an avid tournament fisherman such as myself, complications brought on by the ongoing pandemic were bad enough, but then to show up to some of these ponds and see closure signs from algae blooms was beyond frustrating.

From a saltwater perspective, the impacts of excess N are equally if not more devastating.  The excess N feeds algae to a point where our saltwater estuaries (rivers where fresh meets saltwater) get heavily clouded with algae which prohibits the passage of sunlight needed by eel grass.

Eel grass (and other native vegetation) are known as a “sanctuary” species.  Sanctuary meaning small fish, invertebrates and other aquatic life rely on eel grass to provide protection and habitats for reproduction.  The juvenile herring that leave the freshwater every fall utilize eel grass for cover on their migration back to Atlantic.  Scallops, winter flounder and other species also heavily rely on the presence of eel grass for reproduction.  Without eel grass, reproduction of the species that form the base of the food pyramid are compromised.  Additionally, the presence of excess N and algae can reduce dissolved oxygen levels, turning the estuaries uninhabitable for certain species.

Likewise, in freshwater, the excess P causing algae blooms inhibits beneficial vegetation growth and reduces dissolved oxygen.  As the saying goes, “find the grass, find the bass”, any angler knows submergent vegetation can be a honey hole for largemouth.  Similar to the loss of eel grass in saltwater, the lack of the sanctuary habitat in freshwater also impairs the fishery by eliminating the hiding places for juvenile species to develop.

Where is the N and P coming from

There are multiple sources of excess N and P entering our waters.  There is some naturally occurring N and P, but the biggest man-made source is wastewater (septic systems).  Septic systems are not designed to remove nitrogen and growth in our area has been almost exclusively on individual septic systems.

In the comparison photograph below, the difference between 1938 and 2014 is stark.  This example is of Santuit Pond, commonly closed by algae blooms.  Note the development in 2014 (on the left) vs. the “pre” development conditions on the right.  Each house has a septic system draining to a receiving pond or estuary and all are part of the problem.  In short, we have loved our waters to death.

Each home has a septic tank, ultimately depositing Phosphorous and Nitrogen into the local ponds.
Each home has a septic tank, ultimately depositing Phosphorous and Nitrogen into the local ponds.

What we can do to help

But the good news is, we are also all part of a solution.

Read more about the solution at the Upper Bay Project.

To restore our waters, we must reduce N and P inputs.  Municipal wastewater treatment plants can reduce nitrogen by 90-95%.  Towns in the region are all embarking on aggressive wastewater management strategies.  Dennis, Harwich and Yarmouth are pursuing a regional solution to expand sewers to areas that are reliant on septic systems.  Similarly, Wareham, Bourne, the Mass Maritime Academy, Plymouth and Marion are evaluating a proposed regionalization to expand sewers to residential areas that currently discharge N and P to the Bay removing significant amount of N to Buzzards Bay and surrounding ponds and discharging that highly treated water to the Canal.

While these regionalization projects carry large price tags, doing nothing means the impacts to the waters may become irreversible, and there is no price that can be put on that.  While the thrill of a 5-pound smallmouth or a 40-pound striper can be debated intensely, we cannot debate our responsibilities as stewards of the environment that has provided us with such enjoyment.

The solution lies in education and action.  In these virtual times, contact your Town’s sewer department or wastewater committee (almost all Town websites on Cape Cod and Southeastern MA have links to upcoming wastewater meetings) and voice your concern.  If we all do our part to support wastewater planning, take proactive measures, and get on board, we will make a difference – for the better.

Note regarding the author: Russ Kleekamp is an environmental engineering consultant on the Upper Bay Project.

4 on “Harmful Algae Blooms Threaten Massachusetts Ponds and Estuaries

  1. Mickey Conaughtin

    This is the saddest news of the year. When will my liberal tears stop flowing? My heart breaks again and again.

  2. Timothy Turner

    There is an association between repeated exposure to Cyanobacteria and increased risk of ALS

  3. APEX

    Thank you for raising this issue. This has been a serious issue for the Cape’s fresh water bodies and brackish estuaries for decades and the problem is getting worse. Communities on the Cape and the west shore of Buzzards Bay have been working to solve this problem by expanding sewers and improving wastewater treatment but there is much left to do. De-nitrifying septic tanks have been developed that can remove nearly as much nitrogen as municipal wastewater treatment plants. It all takes money and commitment. We can all pitch in to reverse these trends. Stop fertilizing your lawn. Vote for expanding your community’s sewer district. Retrofit your septic tank with de-nitrifying technology. Stop using phosphate based dishwasher, clothes washer, and cleaning supplies. Stop paving your driveways, put in raingardens at the outlets to storm water discharge pipes. Spread the word.

Leave a Reply

Your email address will not be published. Required fields are marked *