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The U.S. Forest Service calls it the Northeast's 'most vulnerable' due to development pressures.

By JOHN RICHARDSON, Staff Writer July 29, 2009

 

 

 

The forestlands that surround Sebago Lake act like a giant filter and make it one of the cleanest drinking water sources in the northeastern United States.

But, because so much of that forest is privately owned and subject to development pressure, they also make the Sebago Lake and Presumpscot River watershed the region's most vulnerable, according to a new U.S. Forest Service analysis.

"Our watershed is able to provide really good water right now. The challenge is how do we keep it that way," said Paul Hunt, environmental services manager for the Portland Water District, which draws drinking water from Sebago.

The federal report – "Forests, Water and People: Drinking Water Supply and Forested Lands in the Northeastern U.S." – will be presented at a public conference in Standish next week. The water district, as well as the Western Foothills Land Trust and other conservation groups, hope it helps focus attention on protecting the forests that protect Sebago.

The federal study looked at 540 watersheds in 20 northeastern states. Watersheds were ranked as more vulnerable if they produce pristine drinking water for a large number of people; include a high percentage of privately owned forestlands; and face long-term development pressure.

The Presumpscot watershed, as it is identified in the report, rated high in all categories. The Presumpscot flows out of Sebago Lake and therefore shares virtually the same drainage area.

"You think of Maine as a little bit off the beaten path and therefore not as at-risk as watersheds in Massachusetts or New York," said Hunt. "(The top rating) was eye-opening because our water quality is so high."

In some cases, more metropolitan areas don't have Sebago's pristine water quality and therefore ranked lower. In other cases, cities such as Boston and New York have purchased forestlands or development rights around their reservoirs to make sure their watersheds are protected from development pressures.

"We're really trying to emphasize the importance of protecting forests for drinking water supplies," said Martina Barnes, a regional watershed planner for the Forest Service. Protecting forestland is less expensive than leaving it open to development and then having to clean up or treat the drinking water, she said.

The Forest Service found that 73 percent of the Sebago and Presumpscot watershed is privately owned forestland. The analysis also concluded that the area faces significant long-term development pressure.

The forests surrounding Sebago Lake and the rivers that feed into it – the Songo and Crooked rivers – basically soak up rain and snow melt, feeding the rivers and lake with clean, filtered water.

"When you remove the trees and then introduce things like rooftops and driveways and compacted soils, now you have runoff, and anything in or on those surfaces has the potential of reaching your water supply," said Paul Barten, associate professor of forest resources at the University of Massachusetts in Amherst and a co-author of the Forest Service report.

"If you start to clear or lose forests in areas that are currently pristine like Sebago, and if you lose the wrong forests in critical areas of the watershed, you'll start to detect a reduced water quality," he said.

The Portland Water District draws water out of the southern end of Sebago Lake and supplies it to nearly 200,000 people in Greater Portland. It owns much of the land around its intake pipes, but just a small fraction of the overall watershed.

"We own 2,500 acres and the watershed encompasses 300,000 acres," he said. "We sit at the bottom of this funnel and the quality of the water is really a function of how well the forest at the top of the funnel produces water. ... We've always looked at the upper watershed and said, 'Who's going to preserve all that?' "

The water...