Monday, April 21, 2008

Dismal Swamp, Dismal News

One of our local papers reported yesterday on a plan affecting a local wetland. Dismal Swamp is a 660-acre wetland, one of the largest extant freshwater wetlands in Middlesex County. Somehow it managed to avoid being developed during the post-WWII housing boom in Central Jersey. As it is, the tract is already fragmented, with cul-de-sacs and industrial parks carved out and a freight train and gas pipeline running through.

Despite its fragmentation, the swamp retains much of its biodiversity. I was there one evening during breeding season last year and observed 33 species, including willow flycatcher and other characteristic wetland birds. The Edison Wetlands Association estimates a bird list of 175 species, as well as significant numbers of reptiles, amphibians, and mammals. (I am not sure if formal lists exist since their website is difficult to navigate.)

A revived truck route plan may further fragment Dismal Swamp. South Plainfield wants to extend Helen Road to Metuchen Road (see map below) so that trailer trucks can take a shortcut through the swamp instead of driving around it on mostly residential roads. The road would be elevated to contact as little wetland as possible, but it would cut through the wettest area of the swamp. The plan was first proposed two decades ago, but failed to win approval from the state DEP. Earlier this year, the borough council decided to reconsider the Helen Road route rather than look for an alternative.

Dismal Swamp (click to enlarge)

If the state DEP turned down the proposal once, it would probably do so again, with good reason. Even an elevated road would have negative effects on a protected ecosystem. Displacement of habitat by the roadbed – in this case just its supports – are not the only problems. Pollution from runoff and exhaust, traffic noise, and possible introduction of invasive species are some likely problems. There is also a problem that new roads tend to bring new development. Not all of the undeveloped land around the swamp is formally protected, and a shorter route to I-287 could tempt developers to build new housing or industrial buildings on the other side of the extension, which would further increase traffic on already-crowded roads.

I hope that South Plainfield can find a solution for existing traffic problems, whether that means a new route along the edge of the swamp or better use of existing roads. The solution should not be a new road through the middle of the swamp.