Sandy River Delta: Restoring diversity to a complex habitat

Story and photos by Diana Fredlund, Public Affairs Office

U.S. Army Corps of Engineers contractors re-open an historic channel of the Sandy River near Portland, Ore., as part of a habitat restoration project. The multi-agency partnership will allow the Sandy River to create its own path to the Columbia River, creating habitat for young fish. (Photo by Kevin Wingert, Bonneville Power Administration)

U.S. Army Corps of Engineers contractors re-open an historic channel of the Sandy River near Portland, Ore., as part of a habitat restoration project. The multi-agency partnership will allow the Sandy River to create its own path to the Columbia River, creating habitat for young fish. (Photo by Diana Fredlund, Public Affairs Office)

The U.S. Army Corps of Engineers and its partners BPA, U.S Forest Service and the Portland Water Bureau celebrated the first bite out of the Sandy River Delta dam Aug. 15. Corps contractor CEO Kim Erion uses a backhoe to take the first bite out of the dam. (Photo by Matt Rabe, Public Affairs Office)

The U.S. Army Corps of Engineers and its partners BPA, U.S Forest Service and the Portland Water Bureau celebrated the first bite out of the Sandy River Delta dam Aug. 15. Corps contractor CEO Kim Erion uses a backhoe to take the first bite out of the dam. (Photo by Diana Fredlund, Public Affairs Office)

About 70 guests gathered Aug. 15 to watch a backhoe take a bite out of the Sandy River Delta dam, located just east of Troutdale, Ore. The dam removal is part of a habitat restoration project being undertaken by the U.S. Army Corps of Engineers, and its partner the U.S. Forest Service.

The eight-foot tall, 750-foot wide rock and timber dam was built in the 1930s to try to improve fish runs. According to a 1932 article in the Gresham Outlook, a barge sunk in 1907 in the westernmost outlet of the river called the Little Sandy, which effectively blocked water passage. The obstacle forced the water to flow through the east channel, which was considered unfavorable to fish passage.

Although it took years to obtain funding, the Oregon Game Commission – now the Oregon Department of Fish and Wildlife – was able to raise funds more easily after the smelt run collapsed in 1931, when not a single fish entered the Sandy River.  The dam was constructed in 1931, but the smelt runs continued to be very small through the 1930s.After the dam was built, the area downstream of the structure in the East Channel – the original Sandy River – began silting in and losing its complex hydrology.“It was hard even to see where the dam stood after nearly 80 years,” said Gail Saldana, Sandy River Delta Dam Removal project manager. “The stones on top of the dam looked more like a paved path through the trees.”Prior to the dam’s construction, extensively braided shallow-water habitat in the East Channel and abundant backwater habitat throughout the Sandy River delta provided excellent conditions for rearing juvenile salmon and steelhead. After the dam’s construction, the East Channel gradually silted in and became a slough. The delta lost much of its hydrologic complexity and had fewer backwater habitat areas. The dam impeded access and limited cool water flow to the East Channel, resulting in summer ponding and an increased potential for juvenile fish stranding and death.

The Sandy River Delta dam removal was listed in the 2010 Federal Columbia River Power System Biological Opinion as one of the habitat restoration actions the Corps was required to undertake. Planning began in 2010 by identifying the federal and state partners. The U.S. Forest Service manages the land surrounding the dam, the Oregon Dept. of State Lands manages the riverbed and banks up to the high water mark and ODFW manages the wildlife that calls the delta home.

The original plan was for the Corps to cut a 60-foot notch the dam, allowing water to flow freely. Representatives from the Portland Water Bureau learned about the project and wanted to participate.

“The Water Bureau provided funding and technical assistance for removing the rest of the 750-foot dam as part of its 50-year Bull Run Water Supply Habitat Conservation Plan,” said Terry Black, public information officer for the Water Bureau.  “The Habitat Conservation Plan enables the city to meet its Endangered Species and Clean Water Act obligations with 49 separate measures designed to protect and improve aquatic habitat in the Bull Run River and wider Sandy River basin.  We are glad to be working with the strong network of local partners on salmon recovery in the Sandy basin.”

The two-year project proved to be nearly as complex as the delta’s original habitat.  The dam had long been used by Northwest Pipeline, a natural gas provider, and Bonneville Power Administration to reach Sundial Island. “BPA was very supportive in helping us explain the project and encouraging Northwest Pipeline to work with us toward a common goal,” Saldana said. Both companies were concerned about being able to access equipment in the event of an emergency once the dam was removed.

“We had extensive discussions about access,” Saldana said. “After lots of conversations it was decided that the rock from the dam would be stored near the site. That way if an emergency road needed to be constructed, the rock would be easily available.”  Trying to accommodate the often competing needs of city, state, federal and commercial organizations made this one of the most complex negotiations she’d been involved with, Saldana added.

Laura Guderyahn with the city of Gresham shows volunteer Callie Goldfield how to measure a female Western Pond Turtle at the Sandy River Delta Aug. 7, 2013. The U.S. Army Corps of Engineers is removing a dam on the Sandy River and before ponds are disturbed, biologists are trapping turtles and moving them to ponds not disturbed by construction. (Photo by Matt Rabe, Public Affairs Office)

Laura Guderyahn with the city of Gresham shows volunteer Callie Goldfield how to measure a female Western Pond Turtle at the Sandy River Delta Aug. 7, 2013. The U.S. Army Corps of Engineers is removing a dam on the Sandy River and before ponds are disturbed, biologists are trapping turtles and moving them to ponds not disturbed by construction. (Photo by Diana Fredlund, Public Affairs Office)

Once negotiations were complete, preparations for the big dig got underway.  The Water Bureau managed a turtle relocation at the Sandy River delta, in the weeks before construction began. Twenty-four native Western Painted Turtles were captured and relocated to Company Lake, a Port of Portland habitat restoration site that is known to have a colony of Western Painted Turtles.    Although biologists searched the ponds in the East Channel they found no fish to rescue, Black said. “The biologists weren’t completely surprised to not find any fish, since the warm water temperatures aren’t conducive to cold-water fish species.”

LKE, the Corps’ contractor, began construction in the East Channel in early July, digging from the confluence with the Columbia River up toward the dam.  “The contractor is digging a 60-foot wide pilot channel up to the dam, about a mile upstream from the mouth,” Saldana said. “Once the dam is removed the water should flow year-round through the East Channel for the first time in 80 years.”  While the dam was in place, water flowed over the dam on average about 90 days of the year, she added.

Restoring the delta’s diversity will mean healthy habitat for the area’s fish and wildlife species, Saldana said. “This restoration will provide cooler water, additional shallow water habitat and decrease the risk of stranding in the East Channel for ESA-listed species,” she said. “The West Channel should benefit as well by encouraging healthier river banks and returning the channel to a more natural flow.”

Once the dam is removed the contractor will begin replanting and seeding native plants and trees in areas disturbed by construction.  Rootwads – trees with their roots still attached – will be placed along the newly created pilot channel to create shade and hiding places for young fish. “The contractor should be finished with all work by the end of October,” Saldana said. “In all, construction will have taken only about four months. We expect to see the delta start to meander and braid into small channels of its own choosing in the next few years. It shouldn’t take long – Mother Nature is pretty dynamic.”