dam removal becomes more common as dams age and impact river ecosystems

The Winnicut River courses gently under the Route 33 bridge in Greenland and collects in a wide, placid pool that is perfect for casting a line or taking a swim. People sometimes paddle small boats alongside the banks of the impoundment, and on the north side is an inviting section of cropped green grass. The pool spills over the concrete lip of the Winnicut Dam and falls about 12 feet before traveling one mile to the Great Bay Estuary.

In its current form, the dam has been in place since 1957, when it was rebuilt to establish habitat for ducks and other waterfowl. It’s now the only dam left on the main stem of the Winnicut River, and although it provides ample opportunity for recreation, it blocks the passage of river sediment and anadromous fish, the species that mostly live in the sea but breed in fresh water. Since any change to an ecosystem ripples throughout the whole, the dam has also adversely affected water quality, plant life and downstream habitat.

But all that will soon change. 

The state Fish and Game Department, which owns the dam and the abutting property, has decided, in cooperation with other government agencies and nonprofit organizations, to remove the dam and restore the river to its natural state. According to Cheri Patterson of N.H. Fish and Game, the dam removal is estimated to cost between $500,000 and $800,000 and is slated to happen in 2008. There are currently 20 to 25 dams being considered for removal among the 4,800 active and inactive dams in New Hampshire.

“These dams are a product of the way we have industrialized our rivers in the past,” says Laura Wildman, director of river science at American Rivers, a nonprofit organization founded in 1973 that works to protect and restore rivers in the United States. She says that when they were built, most of New Hampshire’s dams were essential to the growth of the state’s manufacturing economy. During the industrial revolution of the 19th and early 20th centuries, they provided hydropower for the mills that popped up in towns like Nashua, Manchester, Franklin and Dover. But since the mills have shut down, the dams no longer serve a purpose.

“A lot of the dams were built at the same time, and all of those dams are getting old at the same time,” says Ted Diers, N.H. Coastal Program manager at the DES. “Repair issues are coming to a head at the same time, and that is one of the reasons that dam removal is hot right now.”

Other Seacoast dams under consideration for removal are the Taylor River Bridge Dam on the town line between Hampton and Hampton Falls, as well as the Gonic Dam and the Gonic Sawmill Dam on the Cocheco River in Rochester. Some conservation groups have called for the removal of the Newmarket Dam on the Lamprey River, but it is not under consideration at this time.

The N.H. Coastal Program completed a feasibility study on the Winnicut Dam in March 2007 to determine if removal was the best option.

“Dam removal is one tool out of many tools for river restoration,” Diers says. “Our role is to determine what are the barriers, impediments or issues. We do not have a policy that all dams should be removed. Our policy is that we want to restore the health of rivers, and sometimes removal is the best option.”

The DES is part of the N.H. River Restoration Task Force, a collection of state departments, federal agencies and nonprofit organizations that meet every other month to discuss ongoing river restoration and dam removal projects. The Task Force provides technical information and channels financial resources to a number of restoration projects in New Hampshire.

The group has been meeting since 1999, but the Task Force officially formed in 2001, when the DES and EPA secured a grant to create a River Restoration Coordinator position in the DES. Deb Loiselle filled that position and concurrently became the chairperson of the River Restoration Task Force.

According to Loiselle, there are adequate funds available for dam removal, but none for dam maintenance. The costs of maintaining a dam usually falls on the individual owner, which could be one person, a company, a government agency or a collection of different parties. They are responsible for paying taxes on the property and funding repairs, and are also liable for any accidents or property damage caused by the dam.

The DES conducts a safety assessment on dams in New Hampshire and determines their hazard levels. High hazard dams receive more attention from inspectors, who decide what repairs need to be made. “If an owner has no use for the dam and they don’t want to repair it, then they look into removal,” DES dam safety officer Grace Levergood says.

Although the DES has started assessing environmental damage criteria for classifying dams, the potential threat of flooding remains a serious concern.

“People have the misconception that all dams are still used for flood control,” Wildman says. But according to Diers, the only dams that provide flood control are those with a very low water level behind the impoundment, of which there are only a few in New Hampshire. Structures where water is constantly spilling over the top receive added pressure in a flood situation. If one were to break, water would rush downstream, causing havoc for the property below the dam. Removal is a more effective flood control method, Diers says.

One dam that is being examined for both its environmental impact and the potential it has to flood is the Taylor River Bridge and Dam, located on Interstate 95. “The highway is the dam, and if there was dam failure, I-95 would wash out into the ocean,” Diers says.

The dam is owned by the N.H. Department of Transportation, which is in the early stages of a feasibility study that will explore a number of options to improve fish passage and avoid flooding.

“It doesn’t need to be removed, in DOT’s point of view,” says DOT Project Manager Robert Landry. “But the bridge is starting to show signs of deterioration and we are trying to be proactive about seeing what the community would like to be done.”

Landry acknowledges that some groups believe removing the dam would help restore the area’s ecology, but he estimates dam removal and bridge relocation would cost $7 million. A more ideal solution, he says, would be to relocate the bridge and reconstruct the dam with appropriate fish ladders. 

The DOT is working with the DES and several other organizations to gather input and secure funding. They hope to complete their study by the end of 2007 and gain funding by 2010. “You don’t do a project of this magnitude without a pretty broad partnership. You don’t do it quickly, either,” Diers says.

One reason it doesn’t happen quickly is because of the cultural and historical ties that many people associate with the dams in their communities. Asking people to remove historical landmarks represents the biggest challenge to removing dams. “There are enormous amounts of sentimental attachment to the landscape that people have grown up with,” Wildman says.

“A lot of folks just like to see the water spilling over the spillway,” Loiselle adds. The N.H. Department of Historic Resources is wary of these projects, according to Diers, but he points out that removing the dam restores the river to its original, prehistoric state.  

Dams located on the Seacoast receive particular attention because of the unique local habitat. Fish that use both the ocean and rivers, such as herring, alewives, shad, smelt and the American eel, which might soon be put on the endangered species list, are undeniably affected by these impediments.

“Dams do have environmental impact. There’s no question about it,” Wildman says.

She encourages people to picture a town with a river through its center that has multiple industrial impoundments and can’t be used for recreation. Such a river turns people away. Compare that to a town with a healthy river that provides economic, recreational and environmental benefits to the community.

“We need to use them. We need to use the fresh water that comes from them. We need to harness the power that comes from them, but we need a balance. We need to manage our rivers in an economic and ecologically sustainable manner,” Wildman says. “The best thing we can do with communities is to let them know what the other vision is, that there is something good for their community that doesn’t include those dams. You have to show them the alternative.”