A new shad-friendly expansion at Holtwood Dam on the Susquehanna River, which had been placed on hold, is back on track thanks to the economic stimulus bill passed by Congress earlier this year.

The $230 million expansion would more than double the generating capacity of the hydroelectric dam while also modifying its fish passage, which has been significantly less effective than what was hoped.

The dam's owner, PPL, had withdrawn an application to the Federal Energy Regulatory Commission in December 2008, citing the poor economy and inability to secure loans.

But the utility resubmitted the proposal to FERC in April, saying the stimulus bill's tax incentives for renewable energy projects that come on line by 2014 made the project feasible again. PPL has also applied to the Department of Energy for a loan guarantee from the stimulus package that would allow it to borrow money for the expansion at a lower interest rate.

"It was really those federal stimulus programs that took a project that had been uneconomical, and made it economical again, and made it viable for us to do it," said George Lewis, a PPL spokesman.

"This was really a shovel-ready project," he said. "All we needed was FERC approval of the application, and it was something that we could certainly complete by 2014 to quality for the tax credit."

FERC approved the application Oct. 30. Construction is expected to begin in the first quarter of 2010 and be completed in late 2012. FERC also approved PPL's request to extend the dam's operating license, which was to expire in 2014, to 2030.

PPL, which said the construction would create 200 jobs, plans to add two new generating units at the dam that would add 125 megawatts of capacity-enough to power 100,000 homes.

The project would also overhaul the fish passage at the dam. A $21 million fish elevator opened in 1997 at Holtwood as part of an effort to complete fish passage facilities at all four hydroelectric dams on the lower Susquehanna. But the Holtwood elevator frequently performs poorly, typically passing only a fraction of the fish lifted over the Conowingo Dam downstream.

Shad find their way upstream by swimming against the current. Fish passages are usually designed to use the flow from power generation units to attract fish to the passage.

At Holtwood, though, whenever the river flow exceeds 31,500 cubic feet per second-a common occurrence during spring shad runs-the river "spills" over the 55-foot dam. That attracts the fish to the base of the dam where they remain, instead of to the fish lift at the powerhouse on dam's east side.

In many years, fewer than a quarter of the fish that are lifted over the Conowingo Dam make it past Holtwood. This spring, of the 29,272 shad that passed Conowingo, only 10,896 were lifted over Holtwood.

For the fish that don't get past Holtwood, the spring migration to spawning grounds is a dead end: Biologists say there is no suitable spawning habitat for American shad between Conowingo and Holtwood.

The power generation expansion at Holtwood is designed to increase the flow near the fish lift and to make several other improvements that will lure more shad to the passage.

The plans also call for increasing public access to the river and improving conditions for whitewater kayaking below the dam.

The construction will begin 100 years after the dam was completed in 1910. At that time, the dam-located 24 miles north of the Chesapeake-was the first major barrier encountered by shad and other migratory fish, closing most of the Susquehanna to spring spawning runs in which fish had once swam as far north as New York.

The Conowingo Dam, located 14 miles downstream, became the first barrier to fish migration on the river when it was completed in 1928.