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Sawmill River returns to more natural course

MONTAGUE — After coursing for more miles beside North Leverett Road in Shutesbury and Leverett, the 3-mile-long Sawmill River rushes beneath Route 63 just east of Montague Center and heads into the village itself and then the meadows and into the Connecticut.

For three decades, conservation groups have been confounded in fixing the problem created more than 70 years ago, when the river was diverted from its natural course into a man-made channel that increased its velocity, causing it to erode its banks and undermine the roadway and bridges.

“We have put so much money and time into emergency repairs,” said Rita Thibodeau, district conservationist for the U.S. Natural Resources Conservation Service a decade ago, looking back on a major washout of Montague Center roads following a 1996 microburst. The washout caused by the river’s flooding cost millions of dollars to repair, yet conservationists knew there were other problems just waiting to happen.

But last week, a half dozen residents and town board members headed down to the riverbank to see the results of a $318,000 effort funded by the EPA and coordinated by the Franklin Conservation District to return a 1,200-foot stretch of the river to its natural course. Another $212,000 in-kind contribution through the mostly volunteer conservation district brought the project total to more than half a million dollars — nearly $442 per linear foot.

Instead of scouring its banks, the waterway was pulled toward the center naturally by two horseshoe-shaped arrangements of boulders, called rock cross-veins, which also serve to slow the Sawmill’s velocity and create a plunge pool that Deborah Shriver, project manager for the Conservation District, said encourages fisheries and other biotic life.

“It makes the fish very happy,” said Shriver, pointing to engineered rock formations along the stretch of river just west of Route 63, before it makes a sharp right-hand turn northward along Main Street into the village. Rather than a homogenous, mostly rocky stream bed, the “bio-engineered” approach is meant to better mimic nature and prevent erosion of the banks — erosion that Shriver said has fed sediment into the Connecticut River and reduced water quality.

Modeling by engineers shows that annual erosion will be reduced from 70 tons to 1 ton a year as a result of the work just completed.

It was a grant from the state that the largely volunteer Conservation District won in 2009, making the point that a newly engineered waterway would avoid town, state and federal dollars having to go into rebuilding roadways, bridges and abutments each time after each serious flood.

Apart from the arcs of boulders, features incorporated by Watertown-based VHB engineers include root wads on either side just downstream from the plunge pools, that serve to collect debris carried by high water, so that the banks build up instead of being washed away, explained Shriver.

To protect the bank from erosion as the river turns northward, SumCo Eco-Contracting installed two 50-foot logs.

The bio-engineered approaches — similar to the nature-mimicking approaches used to prevent erosion along a 20-mile stretch of the Connecticut River — also help the Sawmill flood into its natural flood plain in the case of a major flooding event. An 8-acre area just south of that section of what is the end of Route 47 is owned by the state Department of Fish and Wildlife.

“The river would like to cross the road,” said Shriver, “and have its floodplain on the opposite side. The river was confined in a straightened channel, and that’s an unnatural feature for river.”

To encourage the river to head toward the flood plain, the project, completed in a three-week period last September, included flattening of the bank to the north.

This is the first project of its kind the conservation district has done using rock cross-veins, said Carolyn Shores Ness, supervisor of the quasi-public organization created by the state to promote conservation projects on a regional level.

“We’re very happy with it,” said Montague Conservation Commission member Sean Werle, who took part in last week’s viewing, wearing wading boots and toting a camera. “Now we don’t have to deal with the highway department having to fix the bank. It’s nice to have restorations done properly.”

Montague Town Planner Walter Ramsay added, “This restores that small stretch of the river back to its natural habitat. It’s a great way for the river to kind of recapture its natural flow in a way that doesn’t reroute the river. I’ve seen a lot of fishermen out there lately. It’s a better habitat for fishing.”

The 1,200-foot fix, taking just three weeks to do but 30 years to plan and get funding for, doesn’t address all of the Sawmill’s problems, they agreed. For example, there are still ice jams just upstream, on the east side of Route 63, as well as erosion problems farther downstream.

But, Ness said, given the increased frequency of major storms, it makes sense to invest in a problem that addresses the hydraulics of the river rather than constantly trying to fix roads and bridges destroyed by erosion and flooding.

“This is a one-time fix,” said Shores, who became involved in the district after the Deerfield River’s October 2005 flooding in Deerfield, where she is a selectwoman.

“We are having so many frequent events that are bankrupting us,” she said. “We cannot keep coming back and fixing the same things, and you can’t keep pushing (problems) down the river to somebody else.”

You can reach Richie Davis at
rdavis@recorder.com
or 413-772-0261, Ext. 269

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