Decade After Dam Destroyed, Sandy’s Salmon, Steelhead ‘Rebounding’ – ODFW


Ten years ago a new era of salmon and steelhead recovery quite literally started out with a bang when Marmot Dam was removed from the Sandy River.

Marmot Dam used to block the Sandy River at this bend. Removal of the dam, completed last year, restored the free-flowing nature of the river upstream to its headwaters near the glaciers on Mount Hood. (ODFW)

More than a ton of high-grade explosives were detonated, taking off the face of the 47-foot high concrete dam.

At the time, it was the largest dam breach ever attempted. Portland General Electric, owner of the dam, figured it would be more cost-effective to remove the structure than upgrade it to meet new federal relicensing standards.

Scenes from ODFW’s 2008 “salmon rodeo” on the Sandy: Fish biologists Dannette Faucera and Todd Alsbury point out Chinook redds to their crew while surveying the Salmon River.

In July 2007, in a highly publicized event, PGE blew the concrete face off its dam on the Sandy River. For the next three months, large backhoes with pneumatic hammers pulverized, drilled, pulled apart and hauled off the remaining pieces of the dam. On Oct. 19, a rainstorm swept away the backfill that had accumulated behind the dam, making the Sandy totally free-flowing again, from its headwaters on Mt. Hood to its confluence with the Columbia River in Troutdale 56 miles away.

Biologists, conservationists, anglers, and others hailed the removal of Marmot Dam as a victory for imperiled native runs of Chinook and coho salmon and steelhead. The hope was that fish would benefit from better flows, better water quality and unrestricted access to prime spawning grounds in the uppermost reaches of the river.

DFW staff members unfurl a tangle net before drifting it through a deep hole in the Sandy River. A swimmer, wearing a dry suit, took one end of the net to the other side of the river and swam down and back across the stream in an arc, creating an action in the net that some compared to closing a purse. (ODFW)

So has 10 years of a free-flowing Sandy River been good for fish?

The answer is an unqualified ‘yes’, according to Todd Alsbury, ODFW district fish biologist for the Sandy, and one of the partners in the removal of Marmot Dam.

Fish biologists Todd Alsbury (right), Ben Walczak (center), and Danette Faucera (left), wearing wet and dry suits, wade the icy Salmon River, a tributary of the Sandy, in an attempt to push salmon downstream where they can be collected in a seine net. (ODFW)

Now, for the past three years, when other runs of salmon and steelhead around the region have been down, the Sandy has been seeing increasingly strong returns; in some cases, double what they were a decade ago before Marmot Dam was removed.

“While not solely due to dam removal, returns of wild spring Chinook, winter steelhead, and coho have increased significantly as compared to their abundance before the dam was removed,” said Alsbury, who noted that in the 10 years since Marmot Dam was removed ODFW has observed the largest returns for all three species in the 40 years.

ODFW staff members work together to pull in a net full of fish. Through trial and error they developed a coordinated approach that was very effective at landing Chinook. (ODFW)

For example, the number of wild spring Chinook increased from an average of 809 before dam removal to 2,086 afterwards. Similarly, coho increased from 784 returning fish before dam removal to 1,959 afterward, and wild winter steelhead increased from 898 to 2,757.

To really gauge how successful removal has been, though, it helps to look at how the fish were doing prior to removal of the dam.

Oregon Department of Fish and Wildlife hatchery technicians Rob Dietrichs (right) and Dave VanAmburgh (center) remove a chinook salmon from a tangle net while Dannette Faucera, assistant district fish biologist, prepares to scoop the fish up for transport aboard an ATV, then a tank truck to an ODFW hatchery in Clackamas. (ODFW)

Wild spring Chinook were nearly extirpated in the 1950s and ’60s by dam operations, habitat losses, and other human impacts. During this period, fishery managers tried to rebuild the population with hatchery Chinook, which were intercepted in a trap at Marmot Dam and trucked to Sandy Fish Hatchery, where the next generation of fish was spawned and reared.

However, fisheries management changed dramatically in 1998 when the fish were listed as threatened under the Endangered Species Act. This triggered discussions about ways to recover the fish, including by taking out Marmot Dam and reducing releases of hatchery fish so there would be fewer of them to compete with the ESA-listed wild fish. These discussions also led to one of the first integrated brood programs whereby wild spring Chinook were reared at the hatchery, and later cross-bred with hatchery Chinook to create a fish closely resembling the native fish, instead of looking outside the basin for replacement stock with different genetics.

Members of ODFW fish staff put a chinook salmon into an aluminum box filled with water from the Sandy River. The boxes were strapped to ATVs, which carried the fish about three-fourths of a mile through the woods to a pickups equipped with tanks designed to keep them in good shape during the 20-mile ride to the hatchery. (ODFW)

When Marmot Dam was removed, ODFW biologists lost a fish trap that gave them the ability to catch and separate wild fish. The fish needed to be separated so the wild ones could go on upstream to spawn while the hatchery fish were captured and taken to the hatchery to spawn. For the first two years after dam removal, ODFW staff netted brood stock out of the river using large seine nets pulled by swimmers in full wetsuits. Later on, biologists installed weirs, or portable traps, in the river for this purpose.

To continue providing a recreational fishery, Alsbury and his staff developed an acclimation site to rear and release juvenile fish at a location that is suitable for returning adult fish. They now collect adult fish using temporary weirs near the release location to capture returning adults. Afterwards, the weir can be removed from the river.

“Our goal is to first protect native runs of native salmon and steelhead while at the same time providing a robust recreational fishery,” said Alsbury. “Thanks to a lot of hard work on the part of many dedicated individuals and a lot of collaboration we are starting to see some impressive results.”

“Habitat is the key,” Alsbury added, noting that the Sandy is one of the few rivers where fish habitat is now being added faster than it is being degraded or lost, and that salmon are now showing up to spawn in habitat that didn’t exist before.

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