By Carolyn Kennedy
Orleans has 60 freshwater ponds. Who knew? Some are hidden in backyards known only to salamanders and spring peepers that migrate there each spring to mate and lay eggs. A few lakes are so large that we gather to enjoy swimming, fishing, and kayaking in their waters. Ponds are an important recreational resource for residents and visitors alike.
But just like us, our ponds and lakes are aging. Most are over 10,000 years old. Since their birth from chunks of ice left by a retreating glacier, they have encountered changing environmental conditions and encroachment by humankind. Thousands of years ago they were shaped by surrounding vegetation and climatic conditions. For early human visitors, freshwater was a valued resource making the land habitable. Farming and fishing sustained life. Streams were diverted to increase fisheries, power grist mills, irrigate farms, and grow cranberries. Few ponds escaped human usage and influence.
Today freshwater ponds show their age in various ways and need our help just as estuaries do. Shallow ponds are filling with red maples and turning into wooded swamps. Atlantic White Cedars grow in cool, wet pockets; entering one of these is like visiting a quiet redwood forest with a floor of boggy, wet soil and tall, lush ferns.
Deeper kettle ponds were formed by large blocks of glacial ice. With an underlayment of clay, they retained rainwater and formed a pond ecosystem. What is a bit hard to understand is that pond water is continuous with our underground water supply. Groundwater moves a foot a day toward the ocean and when it encounters a pond it flows through it. Ponds are therefore called “windows on the aquifer.”
Landowners along the up-gradient side of a pond who add fertilizer, herbicides and septic fluids to their soil influence the chemistry of the pond. Nutrients also flow into ponds from stormwater runoff from streets, driveways and parking lots each time it rains or snows. Cedar Pond has an additional source of nutrients – the hundreds of cormorants that roost every night on power lines over it. Groundwater on the down-gradient side is influenced by the conditions in the pond. (Remember, groundwater is the only source of drinking water on the Cape!)
Phosphorus is a missing ingredient in the Cape’s sandy soils but is essential for plant growth. Aquatic plants, from the tiny one-celled algae to waterlilies all need phosphorus to grow. Too much phosphorus makes for a riotous cycle of growth, death, decay and more growth in the next season. Pond water can become poisonous if cyanobacteria colonies utilize excess phosphorus and release their toxins into the water. Ponds like Uncle Harvey’s are closed to human contact by the Mass Department of Public Health when this occurs. Unless we control the phosphorus migrating into our ponds we stand to lose recreational use and their beauty in the landscape. Most Orleans ponds now exceed the recommended levels for phosphorus. And, dissolved oxygen dips precariously low in the summer and water clarity for swimming in compromised.
Fall is a great time to take walks and explore ponds. You will find that some like Boland and Uncle Harvey’s reflect large growths of aquatic plants and very low oxygen in the bottom waters. Others like Bakers Pond and Crystal Lake take water sampling to discover that early symptoms of declining water quality are deep in bottom waters. Shoal and Meadow Bog Ponds are shallow enough for vegetation to have grown across the bottom and therefore provide great food sources for waterfowl. Create your own pond score card, look for each pond’s unique “personality,” and compare it with those published by Orleans Pond Coalition.
We cannot stop the aging process but we can take action to slow it. This winter decide what you can do to improve a pond: plan for a “Cape Cod lawn” using drought resistant grasses and no fertilizer; clean up after your pet every day; work with neighbors on private, gravel roads to divert road runoff away from ponds; take responsibility for eliminating eroding soil on your property or from building lots spilling soil into a roadway; maintain a buffer of native plants along pond edges; volunteer to be a water sampler next spring and join fellow citizens who care for our ponds. We make a difference when we work together.
-Carolyn Kennedy is a member of the Orleans Pond Coalition Pond Protection Committee, and Chair of the Marine and Fresh Water Quality Task Force for the Town of Orleans.