RESTORING A STREAM

Bangor’s Birch Stream has been taken for granted for so long that state environmental personnel aren’t even sure of its source. Due to concerns raised by local residents, the short waterway has gotten a lot of attention recently and been cleaned up. More work remains to be done and a recent report from the Maine Department of Environmental Protection provides many good options.

Birch Stream begins somewhere under Bangor International Airport where it is more a drainage ditch than a stream. After it passes the Airport Mall, however, it flows under trees and over small waterfalls, becoming more streamlike before dumping into the Kenduskeag Stream. The stream is “impaired” in the lingo of the environmental agency. Its biggest impairment is development.

To meet federal and state water quality requirements, the waterway must be made to look and act more like a natural stream, according to the DEP.

The biggest threat to the stream has largely been dealt with. After complaints from residents of a nearby housing complex about the smell of the stream, it was found that de-icing compound from Bangor International Airport and the adjacent Air National Guard base was flowing into the stream. Underground collection devices have largely alleviated that problem.

The major remaining problem is that the stream is surrounded by impervious surfaces – asphalt roads and parking lots that absorb no water, buildings with roofs that force water onto the surrounding parking lots. As a result, rainwater carrying pollutants flows directly into the stream, rather than into the ground as it would in a less developed area.

To combat this problem, the DEP first recommends that the area around the stream be restored by planting vegetation on its banks and by preventing floods, spills and the runoff of road salt into the stream. The second priority is to build detention ponds or other treatment systems and collecting roof runoff to be dispersed into areas where it will be absorbed. The third priority is to convert impervious surfaces into ones that absorb water by replacing pavement with gravel and planting more grass.

The city recently undertook an innovative project that addresses some of these concerns. When it expanded a parking lot near where L.L. Bean will soon open a call center, the city installed small islands of special soil and plants. Runoff from the parking lot will flow into these depressed areas and the water will be filtered through the roots and dirt, which will remove some pollutants, before slowly flowing further into the ground.

Bangor has discovered Birch Stream and done a lot to clean it up. With continued cooperation between the airport, National Guard, city, DEP and area landowners, more can be done.