Prior to our meeting I never thought of a pond as anything having a “life-cycle”. I guess it is because I don’t think of a pond as a single living organism like a plant or an animal. Thinking of it as an eco-system I certainly knew all of the organisms within the pond, or creatures living around the pond had a life-cycle.
It is a fact of life that from the moment you are born, you begin the slow process of dying. Same thing goes for the 80-foot pine trees that are constantly dropping needles, cones and boughs on my house. For a huge pine tree it is a long process. For a pond it is a longer process. For a kettle pond like Sandy Pond it may take until the end of time, but for a shallow flooded meadow like Flannagan Pond, it could take only centuries.
Flannagan Pond was “born” around 1850 when Calvin Fletcher bought 39 acres of meadow just west of Sandy Pond. There was a stream that flowed from Sandy Pond. Fletcher dammed the stream to create a mill pond for his saw mill. This is the granite dam on east main street, about 25 feet or so, downstream from the board dam that controls our water levels. This was before Ayer Junction/South Groton seceeded from Groton and was incorporated as the Town of Ayer.
Calvin Fletcher, seventh child of Pelatiah Fletcher, born in Groton, Massachusetts, February 20, 1797. He was a farmer in Groton and dealt also extensively in lumber. He served the town as selectman, representative to general court, and in other positions of trust and honor. He was one of the prominent men of his day. At the time of his death he owned a large amount of land at Ayer Junction.
The dam backed up water over almost 78 acres, forming what we now call either Flannagan Pond or Fletcher’s Pond. (FYI, we settled on calling it Flannagan throughout all our meetings and correspondence for the sake of consistency). Since the bottom of the pond was meadow, it was covered with rich topsoil, or loam, not a sandy bottom. When saturated with water for years on end, the soil becomes the gooey mess that oozes between your toes when you step in the water.
As the acquatic vegetation took hold, it also continued its cycle of dying and regenerating every year, adding additional muck to the bottom. In addition, we compound that with the trees around the pond that shed their leaves in autumn. Many of these leaves drop into the water and sink. These compost and add more goo to the bottom. So every year, layers upon layer of freshly composted organic matter settles to the bottom, displacing the water, in effect, making the bottom rise and reducing the depth of the pond.
The shallower the water, the more swamplike the conditions. This is a capsule summary of the life-cycle of a pond. The transition from pond to swamp can be retarded though; some approaches provide short-term remediation, such as ongoing weed management. Others provide a longer lasting impact, such a dredging. We will review these methodologies in upcoming installments.
Now for those who argue that we should let nature take its course, I would challenge that thinking. This pond is not a natural body of water. It is man-made. Man deliberately interfered with the natural course of water by plugging the stream, so it makes perfectly good sense to require manmade intervention to maintain the pond created by such action 160 years ago.
In the meantime, please check out some of these resources. You may find them interesting. This text is an excerpt from a pond maintenance company that services privately owned ponds, Sediment Removal Solutions, in Ohio. I thought the author capsulated the process much more eloquently than I did;
“Unfortunately, for all ponds at the moment of birth, they start a dying process. This is nothing to be alarmed about. It is just part of a natural cycle of nature trying to reclaim the pond; transforming it into a swamp, then a marsh, and finally a prairie.
In the beginning our fine-feathered friends bring algae, weeds and eggs to our ponds. The wind contributes leaves, branches, grasses and other material. All of this accumulates in what we call “the bowl” or “septic tank” of the pond, usually the deepest area. In the shallows up to about three feet, live the aerobic bacteria. This bacterium decomposes foreign matter quickly. In the bowl area live the anaerobic bacteria, which cannot decompose the incoming matter quickly enough. This bacterial war rages on and the fallout is methane, sulfur dioxide, phosphates, and other toxic gases saturating into the water column reducing oxygenated water for fish and other aquatic species. This MUCK is nutrient rich and creates a deteriorating cycle. In essence, instead of the aerobic bacteria feeding the planktonic kingdom, and continuing a natural, healthy food chain, the anaerobic bacteria disrupts this natural process and feeds the plant kingdom, increasing algae and weed growth and suffocating the pond. Natural springs and aerators help, but eventually even they lose ground to this natural process.”
Another excellent summary is from Wikipedia on the subject of“eutrophication”.
Eutrophication may be caused by human activity or it may be a natural process. As noted in Part One of this series, ACT’s reports do not suggest that human activities around Flannagan Pond are the cause of our issues, as the nutrient levels of the water to do not support such a claim.
So to summarize, ponds can be thought of as underwater composting operations, that continue to build the nutrient-rich layer of muck that grows thicker with every passing year. So ponds grow shallower year by year, decade by decade. The shallower the water gets, the more swamp-like the conditions.
The next installment will discuss the issue of Dredging.