For salmon, the journey from the Pacific Ocean to their native spawning grounds isn’t easy. But of all the obstacles the fish have to surmount, the most difficult are those that make travel easier for humans.
Culverts have been instrumental in building roads across small waterways. But for decades they were installed without consideration for how they affected migratory fish. Now, armed with better knowledge, transportation agencies are working to upgrade inadequate culverts.
Like most of Washington’s roadways, state Highway 502 was built before people understood how important stream flows are to the life cycle of salmon. So Mill Creek — which runs alongside the highway — was dotted with problematic culverts. Those culverts, and others like them, made whole swaths of habitat inaccessible to migratory fish and other wildlife. Now four of those culverts have been replaced by the Washington State Department of Transportation as part of an ongoing project to widen the roadway.
Culverts can be harmful to more than just fish. Inadequate culverts can fail during high water flows, like one on Highway 4 near the Naselle River did last winter. When it failed it caused part of the roadway to wash away.
Now road agencies like the WSDOT do stream modeling before building or upgrading a roadway, and replace old steel or concrete culverts with ones that mimic the character of the waterway.
“We want them to be fitting with the landscape and work to preserve the riparian corridor,” said Dan Corlett, a landscape architect with WSDOT. That means building culverts so they create different water channels and are wide enough to allow woody debris to pass through.
WSDOT has just fewer than 40 uncorrected culverts in Clark County. But just across the Cowlitz County line, there are more than 30 on tributaries of the Lewis River. However, those figures don’t take into account dozens of culverts owned by local governments or private parties. A 2014 WSDOT report found an average of two other non-WSDOT barriers downstream and five upstream of a typical WSDOT barrier.
Stream-choking culverts are not a new issue for WSDOT, but the issue took on more urgency in 2007.
That year, U.S. District Court Judge Ricardo Martinez found that the state of Washington had a duty to preserve fish runs based on treaties signed with local tribes in the 1850s. In 2013, the court gave WSDOT 17 years to upgrade its roughly 800 fish-blocking culverts on the Olympic Peninsula and around Puget Sound.
“Clark County is not in the case area, but that doesn’t mean we’re not addressing fish passage issues,” said WSDOT regional spokesman Bart Treece. “There are a lot of needs to address … fish passage is another example of where we need to put our resources.”
According to WSDOT, there are about 1,900 barriers in the state highway system, and more than 1,500 of them are blocking significant habitat of 200 meters or more upstream. As of 2014, WSDOT had completed 282 fish passage projects, allowing access to roughly 975 miles of potential upstream habitat statewide.
This year, WSDOT plans to correct 21 fish barriers to open up more than 75 miles of stream habitat.
During the 2015-17 biennium, the state plans to invest about $87.5 million in projects that correct fish passage barriers, and will spend more in the future. Even so it’s highly unlikely every problematic culvert in the state, or even in Clark County, will be replaced.
For example, at Milepost 35 on Interstate 205, a small steel culvert buried far below the freeway pours water about 2 feet down into LaLonde Creek.
“This is likely to never be touched because it’s just too costly,” Corlett said, even though it’s on WSDOT’s list of fish-blocking culverts. “It’d never be done as a standalone project; you’d need to dig up the whole interstate.”