by Barbara Walvoord
When Lathrop East was built, laws mandated that we install systems to prevent rainwater and snowmelt from polluting our wetlands and streams. Run-off carries pesticides, road salt, fertilizer, and other nasty stuff, and is the main polluter of the Connecticut River (Northampton Open Spaces Plan, p. 28).
Our Lathrop systems work in two ways: they slow down the water before it drains into a wetland or stream, or they hold the water until it soaks down into the soil. Both systems use plants, rocks, and soil to filter pollutants.
A slow-down system is visible right behind the Inn, pictured above. Water from the parking lot and Inn roof flows into pipes that carry it to a spillage, where rocks and plants slow its flow down into the wetland.
A second type of system–holding the water until it soaks into the ground–can be seen behind the Huckleberry Lane houses. There, the water runs down the hill, and also through pipes from the road and roofs, into a long swale with a dirt dike that holds the water back from the wetland until it sinks into the ground.
These systems are regulated by state law, right down to the depth of gravel, width of pipe, placement of drainage, length of time that water can stand in a swale (because mosquitoes will breed in it), and so on.
The law treats these systems as drainage, not as wildlife habitat in themselves. You are supposed to mow the swales short, so tall bent-over grasses do not act as an impermeable slide for the water to pass over–never mind the creatures that shelter in the tall grasses. You are supposed to drain the sludge from the swales and catchment ponds periodically–never mind the frogs that live there and the eggs buried in the mud. You are supposed to cut back vegetation that grows around the pipes–never mind the critters who thought they had found a lovely, cool, damp, shaded haven.
Recently, people have been thinking about how to help drainage systems protect wetlands but also act as wildlife habitats in their own right. The Land Committee is looking into these practices. Next time I’ll write more about the catchment pond behind Teaberry–a special case.