A Pennsylvania power company plans to increase generation soon at three dams on the Penobscot River as part of a two-year-old deal to help restore historic runs of Atlantic salmon and other fish in the famed waterway, officials said Tuesday.

In June 2004, PPL Corp. signed an unprecedented agreement with environmental groups, government agencies and the Penobscot Nation to demolish two dams and bypass a third on the Penobscot River. The deal, if fulfilled, would give salmon, alewives and other fish species access to 500 miles of river now largely blocked by hydroelectric dams.

The deal allows the parties involved in river restoration efforts to buy the three dams – located in Veazie, Old Town and Howland – in exchange for a pledge not to fight future relicensing of PPL’s other dams.

In return, PPL was allowed to increase generation at six other company-owned dams to offset losses from the eventual decommissioning of the three dams being sold. Company officials said Tuesday that PPL will ramp up its generation at its Medway, West Enfield and Stillwater dams in the coming weeks.

PPL and the Penobscot River Restoration Trust will discuss the restoration efforts during an event in Old Town today. Representatives of the Penobscot River Restoration Trust also will give an update of its campaign to raise $25 million to purchase the dams by the June 2009 deadline.

Laura Rose Day, executive director of the nonprofit organization, said the trust has raised about one-third of the money but would like to see more coming from the state and federal governments.

“Private donors have really stepped up to the plate because they respect the innovation and collaboration of the project and the enormous ecological and economic potential of the project,” she said.

Day also called PPL’s energy increase “a great milestone” on the road to fulfilling the agreement.

PPL officials said they hope to generate collectively an additional 10,000 megawatt-hours of hydropower annually – enough to power 1,000 homes – from the improvements being made to the three dams. To increase generation capacity, PPL plans to raise the water levels at the dams by 1 foot.

During interviews in Bangor on Tuesday, company officials said raising the water levels should have no dramatic, negative impacts on area landowners. PPL spokesman Paul Wirth said the public will benefit from the “clean,” pollution-free hydropower.

The Federal Energy Regulatory Commission and the Maine Department of Environmental Protection have authorized PPL to increase its power generation from dams by more than 25,000 megawatt-hours during the next four to six years. Wirth said PPL has no immediate plans to increase generation above the 10,000 megawatt-hours announced Tuesday.

“There can be other expansions, … but we really have no commitment at this time to expand further,” Wirth said.

At the time of its signing, the river restoration agreement was hailed by environmentalists, business leaders and government representatives as a model compromise for restoring fish habitat.

The Penobscot River is home to the largest population of returning adult Atlantic salmon in the United States, but the 700 to 1,300 adults counted in recent years is a fraction of the river’s historic spawning figures.

Today’s event will be held at 1:30 p.m. on the banks of the Penobscot in Old Town’s Spencer Park.