by Barbara Walvoord
On the east campus, behind the Teaberry Lane houses, near the blue garden shed, is a beautiful little pond, full of native cattails, with grasses and wild flowers along the edge.
But also along the edge, you may see a piece of thick black rubber exposed under the grasses and stones. That’s your clue that this is what the state of Massachusetts Department of Environmental Protection handbook calls a “wet basin with impermeable bottom.”
That means the pond was created to catch and filter the storm water, which contains salt, oil, fertilizers, herbicides, and other pollutants, before that water drains into the adjacent woods and wetland.
The stones along the slow down the water and allow some of it to soak into the ground before it even gets into the pond. Within the pond itself, you can see the drain at one end, and then, if you walk into the woods, you’ll see where the drain comes out into a trough filled with stones.
Also at the edge of the pond, you’ll also see the electric box that powers a fountain in the middle of the pond that keeps the water moving to reduce mosquitoes (which breed in still water) and algae (fed by the fertilizer we use on the adjacent grass).
So unlike our vernal pools, which the glaciers put into our woods and which we let nature manage, this pond is human-managed.
The state treats this as a drainage mechanism. It requires that we keep the drain cleared of vegetation, which is why you might have seen our workers in there last summer in their wading boots cutting back the cattails. We should also drain the pond after a certain number of years, because the rubber bottom can get covered with mud that is increasingly toxic, and eventually fails to capture the toxins in the water.
But our pond is not just a drainage pond–it’s a home. If you walk along the edge in summer, you’ll hear the plop plop of frogs hopping into the water ahead of your feet. The frogs have not read the DEP handbook, so they, along with the salamanders, dragonflies, and other creatures, think it’s a regular pond. Our pond is a source of pleasure, too, for us residents who walk by, or view it from our homes.
So we have to manage our special pond in a special way, trying to protect our woods and wetlands from polluted storm run-off, trying to protect the plants and creatures that call this pond home–and also provide a beautiful pondscape for our residents and visitors. A movement called “low impact development” is working on these problems. See the EPA websites: http://water.epa.gov/polwaste/green/ and http://water.epa.gov/infrastructure/greeninfrastructure/index.cfm.