news-180429932-ar-0-torlyrakidjl.jpg
File photo / Mail Tribune Oregon Department of Fish and Wildlife fish biologist Dan VanDyke measures the depth of Bear Creek on the upstream side of a barrier to fall chinook under Jackson Street bridge in Medford in October.

I-5 viaduct concerns drag out fish barrier removal

When then-Secretary of the Interior Bruce Babbitt took the first sledgehammer whack toward dismantling Bear Creek’s Jackson Street Dam in 1998, he hailed the Northwest’s first dam removed for wild salmon as the dawn of easy fish passage through downtown Medford.


But Babbitt’s he-came, he-sledged, he-left ceremony 20 years ago turned out to be more pomp and circumstance than substance.


While fish passage has improved with the dam’s removal, barriers remain the bane of wild salmon in the Jackson Street Bridge area, where fish must now swim underground and then over a 4-foot-tall abandoned sewer pipe exposed last year by erosion.


But that could finally change thanks to the abandoned pipe and an Interstate 5 viaduct that doesn’t have an embedded leg to stand on.


Plans for a quick-fix removal of the pipe have stalled because the Oregon Department of Transportation wants an engineering study to ensure that the move won’t over time trigger erosion problems around a viaduct footing about 500 feet upstream of the pipe.


It’s one of 39 viaduct footings at risk of erosion from Bear Creek because they’re secured to underground concrete slabs and are not anchored into bedrock, according to ODOT. The other nine footings are similar but not at risk of erosion because of their locations, ODOT says.


The study also will create an opportunity to recontour that stretch of the creek so future barriers don’t rear their ugly heads.


“I think already the dam-removal project has contributed to a lot of healing in Bear Creek,” says Dan VanDyke, Rogue District fisheries biologist for the Oregon Department of Fish and Wildlife.


“But once this final fix is done, I think it’s going to be another part of the healing and those promises from ‘98 will be getting taken care of,” VanDyke says.


Bear Creek is one of the most pummeled urban streams in Oregon, violating myriad water-quality standards that have led to spray-painted “Mr. Yuck” signs warning people not to have contact with the creek and to curb further dumping of urban pollutants into it.


For 34 years, the 11-foot-high dam downstream of the Jackson Street Bridge was the focus of the creek’s woes. Created to divert irrigation water, it sported such a poor fish ladder that salmon migrating upstream would miss it and jump futilely onto its concrete base. Also, it blocked juveniles from moving upstream past it during summer, when the creek’s all-wild salmon need to take refuge from heat by reaching Ashland Creek and other cold-water streams.


The city of Medford raised $1.23 million and garnered public support for over a decade before the dam’s removal in July 1998. But high-water events over the ensuing years has led to erosion working itself upstream from the former dam site.


This so-called “head cut” erosion is blamed for scouring the creekbed immediately downstream and upstream of the Jackson Street Bridge, initially carving out a pool that was as much as 4 feet below a concrete-and-rock lip originally constructed to protect utility lines that ran east-to-west under the creek.


Like the old dam, this impediment blocked fall chinook and threatened wild coho salmon from heading upstream under low-water conditions and blocked juveniles from moving upstream past downtown.


Still, enough fall chinook got past it that fish have been spotted spawning as far up as lower Ashland Creek each year since 2011, VanDyke says.


Further erosion last year created all new passage woes there.


The creek ate away rock just upstream of the bridge, exposing the old sewer pipe while scouring out the ground beneath the concrete lip. Now, a ribbon of water flows over the pipe before falling 4 feet to a small pool and then running underground into the downstream pool.


Last fall, enough chinook successfully swam through that tunnel and over that pipe to make it all the way to Ashland Creek for spawning, VanDyke says.


The city of Medford cleaned the pipe and capped both ends for what was initially thought to be a quick removal of it during the summer window when construction is allowed in wild salmon streams.


Then ODOT, and later the Rogue River Valley Irrigation District, raised questions about whether removal would allow more erosion to work upstream toward the new irrigation diversion or the viaduct abutment.


“Right now, it’s ready to go, or it’s ready to stay,” Medford Public Works Director Cory Crebbin says.


Jim Collins, ODOT’s regional geo-environmental manager, says his agency won’t sign off on any removal until it sees an engineering study with a design that won’t threaten that abutment, which in transportation lingo is called a “dent.”


“That was a game-changer,” VanDyke says. “I knew then there was no way this was going to be a quick project.”


It may take as many as two years to garner the necessary permits, studies and other analyses to create a project that would meet ODOT’s concerns.


“That’s not a trivial analysis,” Crebbin says. “It’s going to take time and money.”


But so far, no one knows how much, when and from whom.


“As near as I can tell, no one has agreed to anything and come up with a concrete course of action,” Crebbin says.


While ODOT’s concerns trigger the technical review, the agency can’t fund any of that engineering or design because it’s not technically a road project.


“There’s no way we can spend gas-tax dollars to do that,” Collins says.


ODOT will, however, offer technical assistance in an advisory capacity, Collins says.


In the meantime, it’s more of the same for this summer’s juvenile salmon heading upstream out of the hot downtown flows and for fall chinook adults’ upstream migration in autumn.


VanDyke says biologists expect to place some temporary structures such as sand bags to push more water toward the west side of the pipe, creating more flow over a shorter area for salmon to better navigate the pipe.


Reach Mail Tribune reporter Mark Freeman at 541-776-4470 or mfreeman@rosebudmedia.com. Follow him on Twitter at www.twitter.com/MTwriterFreeman.

Share This Story