The salmon that call the south fork of the Necanicum River home should have a much friendlier habitat, thanks to a water diversion dam update begun last year.
The project reduced the size of a water diversion dam in Seaside’s watershed on the south fork of the Necanicum River, 1.5 miles upstream from the confluence with the mainstream Necanicum, and updated the city’s reservoir at Peterson Point. The project will conclude this month, Wallace said.
In July 2012, crews began work on the project, which was a partnership of numerous agencies, including the Necanicum Watershed Council, Oregon Watershed Enhancement Board, U.S. Department of Fish and Wildlife, Oregon Fish and Wildlife, the National Oceanic and Atmospheric Administration's American Rivers program and Longview Timber, which contributed funds to finance the bulk of the project.
"There's about $850,000 or $900,000 brought to this project," said Seaside Public Works Director Neal Wallace. "Almost none of that was the city's."
All the city had to do was make Wallace available to work on the project and pay for "a few peripheral things," he said.
The dam, which had been raised to 8 feet in 1951, was too high and caused water to rush over in one concentrated area.
"With that increased elevation, water spills over the dam," Wallace said, and the river bed "was mostly down to bedrock. It doesn't have good habitat function. The dam is an impediment to fish passing."
Salmon require a more gravel- and sediment-rich habitat, which the project addressed. The old fish ladder, which was intended to aid fish passage over the high dam, was outdated, ineffective and a "barrier to sediment transport downstream," Wallace said.
"For at least part of the stream, you're to affect spawning habitat," he added.
Waterways Consulting, of Portland, and its lead scientist, John Dvorsky, helped craft a plan to tackle these problems.
A notch was carved into the center of the dam to reduce it to its original 6-foot height, and the cutting was feathered out to the edges, which were also lowered, allowing water to pass over the dam more evenly year-round.
Restoring the salmon habitat meant more than simply fixing the dam: A new, rotating, battery-powered plastic fish screen replaced the old metal models, which still allowed smaller fish through.
As water flows over the dam, it is diverted through a literal water shed, where the new fish screen stands. Water passes through the fish screen and into a tube that heads downhill toward Seaside's reservoir, while the fish swim through an alternate pipe that feeds back into the Necanicum.
The crews also installed a number of rock weirs, which help control the water's elevation and will create small resting pools for salmon, and tons of rocks were brought in to transform the riverbed from blasted-out bedrock to a "roughened channel."
"It was very intentional, the way this was done," Wallace said. "In a few years' time, this will look much more natural."
The dam and salmon habitat portion of the project was paid for by a grant from the U.S. Fish and Wildlife Service.
Maintaining a consistent output of water to the city of Seaside during this project was important to everyone involved. This is where updating the water pumps at Peterson Point came in.
Part of the project involved updating the city's water pumps at Peterson Point, which were over 50 years old and required regular oversight. They "would actually catch on fire if you didn't have someone keeping an eye on them," said Melyssa Graeper, director of the Necanicum Watershed Council.
"We were hitting the south fork as hard as possible because these were so unreliable," Wallace said of the old pumps.
The new variable speed energy-efficient water pumps run automatically and represent a $100,000 upgrade for the city. The pumps were paid for by a grant through the Oregon Watershed Enhancement Board.
Installing the pumps was the first piece of the project and was finished last year, ensuring that the city's water supply was never altered or compromised. Crews also installed a state-of-the-art fish screen at the Peterson Point site.
The end result is a "really nice channel that fish can get through at all times of year, yet the city is still meeting the water need," Graeper said.
Amy Horstman, of U.S. Fish and Wildlife Service's Habitat Restoration Program, "really championed the project," said Wallace.
"This is an excellent partnership," Horstman said. "We weren't going to do anything that wasn't going to benefit the city or maintain their water rights and their needs."
"We didn't just want to make this just about a fish project – this had to make the city happy," Graeper said. "It works for the fish, yes, but ultimately it works for the city."