Coming down

For the past 25 years, advocates for the river have been pushing to remove three dams that have obstructed fish spawning, encouraged invasive plants, and worsened pollution.

Their efforts will bear fruit in the next few weeks, as work will begin on dismantling the dam at Wapping Road. Then attention will shift to the two remaining dams.

“It’s not just about the fish but about why they matter - fishing for recreation and livelihood, fish as a food source for wildlife, for larger fish, for us,’’ said Pine duBois, executive director of the Jones River Watershed Association, whose goal is to restore the 7.5-mile Jones River as an efficient conduit for Silver Lake and Cape Cod Bay.

The history of dams on the Jones River begins in the 1640s, with the first granting of a “privilege’’ to harness water power with a dam. One proviso was the removal each spring of the log structures to allow passage for spawning fish.

But with the Industrial Revolution and the advent of concrete, the rewards of full-time productivity from permanent dams overrode the centuries-old understanding of the importance of a self-replenishing fish population. In the early 1900s, dams at Elm Street, Wapping Road, and Forge Pond were made permanent with poured concrete.

Over the years, there have been attempts to maintain the aquatic population by annual restocking - without success. The last herring count, taken by watershed association volunteers during the latest spawning season at the Elm Street fish ladder, found 363 from April 6 to May 29, translating to 3,011 herring in the entire river, based on state projections, said Alex Mansfield, the association’s ecology program director.

“We should be seeing hundreds of thousands and shouldn’t even be able to count the fish when they’re running,’’ said duBois.

The dams have also harmed the water’s health, with blocked water warming in the sun to the detriment of native fish, while proving a boon to bacteria and invasive plant species. The depleted oxygen levels and warm water temperatures make it unsuitable spawning grounds for those fish that do manage to reach it.

The dams also trap sediment that can contain contaminants from decades of dumping by the mills, such as the Mayflower Worsted Co., which closed at Wapping Road in the 1960s. Pollutants from outside sources, such as fertilizer and road run-off can also settle in the stilled water.

As a stopgap measure, Kingston installed in 2001 a fish ladder - a long ramp with “baffles’’ that create eddies to help fish, including sea lamprey, some sea run trout, and river herring, swim up the ramp. But the dam is still an obstacle for many fish, including shad and rainbow smelt, according to duBois.

Initial steps to remove the Wapping Road dam began in 2007 and 2008, with surveys to assess the potential for the project and evaluate alternatives, such as fish ladders and bypass channels. But the only option that seemed to provide long-term success was full removal of the dam.

But removal is a complicated process, and the 47-foot-wide and 6-foot-high Wapping Road dam required three years of studies, monitoring, permitting, design, outreach, and now removal and river restoration at a cost of $740,000, according to Mansfield.

The bill is being footed by the federal and state government, as well as the town of Kingston, the Sheehan Family Foundation, and Wapping Road property owner Dan Galambos. Water at the dam has eroded the land at the front of his business, Caton Connector Corp., and Galambos has donated money as well as land for the construction crew’s use and later, for a park.

“It’s hard to put a dollars-and-cents value on an environmental resource when you’re considering immediate gains,’’ said Mansfield, referring to installation of concrete dams and present focus on quick fixes. “In the long run, it’s more expensive to solve problems later than address them responsibly in the first place.’’

Once the Wapping Road dam is removed, the site will be monitored for three years. DuBois said she expects to see improved water quality, rebounding species diversity, and miles of upstream and tributary access for fish now impounded between the Wapping Road and Elm Street dams.

If all goes as planned, state money will come through to allow the dismantling of Forge Pond dam about 3 miles upstream. Massachusetts Division of Marine Fisheries project manager Brad Chase leads the Forge Pond dam project, and Mansfield expects the project to proceed later this year.

The process may be helped by a trend toward dam removal after a number of incidents pointed to aging dams as a risk not only to fisheries and water health but public safety.

“Whether it’s global warming or natural variation, we’re seeing more floods in the past few years, and perhaps the most recognized one was in 2005, when Whiton Pond dam almost failed and caused the evacuation of downtown Taunton,’’ said Eric Hutchins, National Oceanic and Atmospheric Administration marine habitat resource specialist.

Though no one knows the number of dams in Massachusetts, there are 2,894 registered dams in the state, and hundreds of thousands that don’t meet the full definition, according to Hutchins, who often finds unmapped dams while hiking or canoeing in the woods.

Removing the old dams - often nothing more than the original wooden structures covered in concrete and never meant to deal with major storms - picked up in the late 1990s, with the first proactive habitat restoration in 2001. There are now more than 50 dams being evaluated, and probably well over 100 being considered for studies, according to Hutchins.

As dams age, they falter. The Wapping Road dam nearly failed in the spring of 2008 when a gate rusted away and blew out, emptying the impoundment and sending water rushing under the building with such force that it was nearly destroyed .

Now, the dam’s removal is considered a “high priority” project by the state’s Division of Ecological Restoration, because it is considered to have the potential of causing fatalities as defined by the US Interagency Committee on Dam Safety.

Failing dams are costly, requiring some landowners to sell them to municipalities for $1, such as the Billington Street dam in Plymouth, where trapped sediment and dam removal ultimately cost about $1 million.

A more felicitous outcome was the removal of the Briggsville Dam in Clarksburg, which kept owner Cascade School Supplies, one the Western Massachusetts town’s largest employers, from closing.

Hutchins is optimistic that funding will come through to tackle Forge Pond dam, bringing the Jones River that much closer to providing unobstructed passage for spawning fish. “There is a bigger issue here than just taking care of fish, and there is a lot of support for this project.’’

Constance Lindner can be reached at cl0734@gmail.com.