Community Environment Government

Purdy Creek culvert projects completed to salmon’s liking

Hundreds of salmon swam up Purdy Creek to Highway 16 last fall. There, they didn’t need to surmount a 262-foot pipe of rushing water to reach the other side. They just continued upstream to spawn as if it was pre-1978.

Forty-seven years ago, the state Department of Transportation built a divided highway bypassing downtown Purdy. Workers laid a 6-foot-diameter steel pipe in the stream bed, buried it under 40 feet of dirt and built the roadway across the top.

Crews returned in fall 2022 to reverse the process. They installed a 206-foot-long bridge for each direction, carved out the fill beneath them to reclaim the valley and restored the stream to a likeness of its original self.

Project Engineer Justin Janke, center, Field Engineer Adam Worden and Communications Consultant Angela Cochran led a reporter on a site visit Thursday. Photo by Ed Friedrich

The $41.6 million fish passage project, which included replacing another old culvert with a bridge where Purdy Creek enters Burley Lagoon, was “substantially complete” on Dec. 5. Lead contractor Kraemer NA finished the work 85 days early, said WSDOT Project Engineer Justin Janke, though planting is still wrapping up.

Janke, Field Engineer Adam Worden and Communications Consultant Angela Cochran led a reporter on a site visit last week.

How does it look?

The creek is running a little brown after days of heavy rain. It’s but a glimmering sliver swallowed by valley walls. Fifteen thousand plants, each cupped by soil pockets, create a purplish moiré on the hillsides. They are no more than sticks with buds, but in time will solidify the bank and provide habitat for fish and wildlife. Rows of staked sandbags draw lines across the landscape and help hold everything in place.

The bridges above, comprising some of the largest concrete girders fabricated by the state, cast shadows across the basin. The beams needed to be transported on 18-wheeled heavy hauler trucks and emplaced using three cranes.

Thirty-seven logs rest in, along and across the creek to prevent scour and provide refuge. Some stand upright like telephone poles to catch debris during high water. Six-foot-tall buried revetments made of large boulders act as hidden levees to keep the stream in its banks and away from the bridges.

“Most of what you see accommodates flooding events,” Janke said. “Stream design is driven by hydraulic models.”

Workers reported seeing up to 300 salmon upstream of the new bridges during their November run.

A chum salmon swims upstream to spawn last fall. Photo courtesy of WSDOT

“In December we went down there and there were a couple hundred chum dead on the side of the creek, so they definitely made it up there and spawned,” Worden said. “You could definitely tell they were there (by the rotting carcass stench). They made it through both of our (Purdy and Highway 16) crossings.”

Creating a new stream bed

The creek was diverted through two 15-inch plastic pipes while the new stream bed was created. The old culvert was “de-fished” before the shift, during the July 16-Aug. 31 fish window that reduces the risk of harming fish at sensitive stages. Biologists found coho salmon, sculpins, lampreys, cutthroat trout and crawdads.

The new stream bed was sealed to keep the water from going underground. Workers spread a layer of mixed cobbles and sediment, then watered in sand to fill voids until it was watertight. They repeated the process two more times, to a depth of three feet. Round rocks were scattered on top.

Thousands of native plants were sown in 3 inches of bark mulch mix on top of 3 inches of fine compost. The types change as they climb from the creek bed. A riparian plant mix starts at the stream, stepping up to a median shrub mix and then an upland mix at the top.

The eastbound Highway 16 bridge casts a shadow across the creek and plantings. Photo by Ed Friedrich

Species include sword fern, cascara, tall Oregon grape, osoberry, western hemlock, salmonberry, snowberry, Douglas fir, Wood’s rose, hazelnut, ocean spray, thimbleberry, red elder berry, red osier dogwood, Pacific ninebark, Sitka willow, Hooker’s willow, vine maple, western red cedar and Oregon ash.

Projects prompted by court order

The Purdy Creek project furthers the state’s efforts to satisfy a 2013 federal court injunction initiated by 21 tribes that requires it to restore access to 90% of blocked fish habitat under western Washington state roads by 2030. As of June 2024, WSDOT has corrected 146 culverts and improved access to 571 miles of blocked salmon habitat within the injunction area, according to its website.

As a bonus, the Highway 16 project created a wildlife crossing.

“I think it will be awesome for fish and wildlife,” Worden said. “I think the fish will love it, and hopefully we can stop having the deer cross the highway. I think it will be a benefit for multiple species.”

“I think it’s an awesome outcome, a good final product,” said Project Engineer Janke, emphasizing the coordination of the many partners that made it happen. Besides WSDOT, they include Kraemer NA, state Fish and Wildlife, state Ecology, public information office, Squaxin Tribe and environmental companies.

Culvert waiting to be replaced at 144th Street. Photo by Ed Friedrich

Two county culverts continue to block

Two Pierce County-owned culverts continue to partially block 6.5-mile Purdy Creek salmon. Just 110 yards upstream from the state’s Purdy culvert replacement, fish confront a 320-foot-long system of culverts that extend under a Chevron gas station and 144th Street. Fast and shallow water block 67% of fish, according to Fish and Wildlife. There’s another one on 160th Street, a dead-end road along the Pierce-Kitsap county line where a drop-off from the 4-foot concrete pipe’s outlet to the stream prevents 67% of fish from passing, says the state.

In May 2018, the county and state completed a joint study of the gas station barriers, but the county can only afford about two fish-passage projects a year and isn’t driven by a court case.

In May 2024, the county completed a draft culvert prioritization list. Both Purdy Creek culverts are among the 15 listed as top priorities. The Chevron/144th Street work is estimated to cost $15 million, the 160th Street job $4 million.

The 160th Street project is advancing through final design. Construction is anticipated to begin in 2027, said spokeswoman Amanda Smith. Though the 144th Street project ranks high on the list, it has yet to be funded.