Fern  Ridge  Dam  project  Ready  To  Flow
September 21, 1998
©The Register-Guard - Used with permission

Underwater amphitheater? Not even.

A $200,000 fish pond? Not on purpose.

That puzzling project at Fern Ridge dam that's drawn gawks from motorists on Clear Lake Road for the past two months will be ready within days for its intended purpose: hydraulic energy dissipation.

"The water comes gushing out of there and causes a cavitation, and we've been concerned about that because eventually it will mine away at that bank," says Rick Hayes, a ranger at Fern Ridge for the U.S. Army Corps of Engineers.

Translation: As water has been released in the past from the dam's flood gates, it surged across a flat, concrete spillway and then swirled violently into a pool of its own making, taking frequent bites out of the piled-rock embankment.

So the corps, which operates the dam and its 9,000-acre flood-control reservoir, contracted for $202,000 with Capital Concrete Construction Inc. of Salem to extend the spillway, deepen and broaden the pool and shore up its exposed bank.

And the engineering maneuver has produced some eye-catching moments, beginning with the complete - though temporary - diversion of the Long Tom River last month as it emerged from the dam 15 miles northwest of Eugene. A huge funnel-type device was placed against the floodgate, and a 4-foot-high culvert rerouted the river for several hundred feet to give the construction crew a relatively dry work site in the usual streambed.

"It's been a battle, dealing with the water," project foreman Dean Prondzinski says as he uses a trackhoe tractor to pull the disassembled pipes out of the spillway. "We've gotten a lot of learning experience from this one.

"There was, like, 54 cubic feet per second going through that pipe. It was a lot of water."

Then there was construction of the semi-circular, layered retaining wall made up of about 75 canvas "pillows" - each 10 feet long by 5 feet wide and filled with concrete. The pillows were stacked in a stadium-shaped configuration that will provide comfortable cheap-seat views of fishing in the pool below.

"If nothing else, it's going to be the world's best crappie pond, with that cement bowl ... and almost the lawnchair seating," says Hayes, the Corps of Engineers ranger. "I hope it works from the erosion standpoint, also."

Actually, it's the carp population rather than crappie that has caught the construction

crew's attention. The lumbering bottom-feeders were spooked by initial stages of the project, but during the removal of diversion pipes at least a dozen carp upward of two feet long have been swimming near the feet of wading workers.

"The fishermen are going to like this," Prondzinski says.

A "pre-final" inspection of the work is scheduled today, with normal operation of the dam expected to resume by midweek.

The project is running about a week ahead of schedule - the annual draw-down of the lake, to make room for winter rains, is to begin Sept. 29.

"That was kind of the `Get your stuff out' deadline," Hayes says.