HOWLAND, Maine — Preparation work for the construction of a $3.2 million fish bypass and the marketing of the former Howland tannery site are underway, officials said Tuesday.

Workers from SumCo Eco-Contracting LLC were installing security fences and silt control devices at the site this week. They will continue the construction work through the winter, with the bypass of the Howland Dam on the Piscataquis River expected to be finished by fall, said Laura Rose Day, executive director of the Penobscot River Restoration Trust.

“Sea-run fish need to get into the really important habitats of the headwaters of the river,” Day said Tuesday. “The area around Howland is really important. The beginning of the Howland phase of the project means beginning the last major step to that process.”

The bypass is part of the Penobscot River Restoration Trust’s plan to open nearly 1,000 miles of habitat to endangered Atlantic salmon, sturgeon, American shad, alewives and seven other species of migratory, sea-run fish now blocked from going past Howland. Those species help support other commercially important species, such as cod and lobster.

Made up of a coalition of organizations, the restoration trust bought the Veazie, Great Works and Howland dams from PPL Corp. in December 2010 in a historic deal worth $24 million. Under an agreement brokered in 2004, PPL in return gained authorization to increase power generation at six other dams along the river, entirely offsetting the generation losses incurred when the three dams were decommissioned.

The Veazie Dam was breached in stages during several months of 2013. The Great Works Dam, which stretched across the Penobscot River from Bradley to Old Town, went down in 2012. The Howland Dam near the confluence of the Piscataquis and Penobscot rivers remains in place but does not generate electricity.

A count last summer of the number of fish using a fish lift that the restoration trust installed in the river in Milford indicates that the trust’s plan is working. Just over 800 American shad passed though, with more than 160,000 alewives, but fewer than 300 salmon, Day said.

“Restoring a river that has had these dams on it for more than a century doesn’t happen overnight, but we are seeing some very promising signs of recovery,” Day said.

The tannery site, which comprised one massive building and two smaller ones, was razed in 2012. Town leaders had been working to redevelop the site since 1972. For decades the tannery was a blighted hulk at the center of town, symbolic of the community’s economic doldrums, but the riverside plot, with its ready access to Routes 2 and 155 and Interstate 95’s Exit 217, is among the area’s prime spots for economic development, officials have said.

With Selectman Joseph Dunn arriving after the vote was taken, selectmen voted 4-0 on Dec. 8 to hire economic development planner Elizabeth Della Valle of Portland for $22,000 to develop concept and marketing plans for the site. Della Valle signed her contract last week and will likely start work after Jan. 1. She was one of two finalists who bid for the work, Town Manager Tracey Hutton said.

“As the feasibility study gets underway and construction gets going, it is going to be interesting to see how it all comes together. I don’t think we will be able to predict what it’s going to mean for the town just yet,” Hutton said.

The site has already drawn serious interest from three businesses, said Glenn Brawn, chairman of the Board of Selectmen.

“Actually, I wouldn’t be surprised if I could have an announcement [of site development] for you early next year. I am putting myself out there and may get my wings clipped but I am really excited about the potential for development here,” Brawn said. “I think we need a very good approach to that property to utilize that space to the fullest benefit to the town. Obviously, we would love to see new jobs created.”

Brawn said he hopes that the bypass will be a tourist attraction and draw fishermen.

“We are definitely ripe and ready to get some development in there and turn this town around and start building its tax base,” Brawn added.