Skyline underpass waterlogged in first weeks of spring
There’s a new pond near Cooper Landing. It formed as snowmelt and drainage from a creek pooled in the underpass at the bottom of Skyline Trail, blocking hikers from going under the highway to get from the parking lot to the trailhead.
The underpass is new. It was built in 2019 and cost the state just under $400,000, as part of a larger Sterling Highway rehabilitation project.
Now, it’s unpassable because of all the water. Department of Transportation spokesperson Shannon McCarthy attributes the blockage to ecology changes in the area.
“The fire in 2019 that really burnt a lot of foliage, a lot of trees, shrubs, grasses and other plants, allowing the water to come down the hill," she said. "It’s actually created a new creek that we didn’t have in this area before.”
That was because the wildfire changed the ground cover. It was a problem last year, too, and DOT created a settling pond to hold extra water and riprap to prevent erosion. But this year, there’s more water above ground than the drainage can handle.
Part of that, McCarthy said, is there’s more snow this year, melting all at once. The ground is also still frozen so water can’t infiltrate.
Deputy Refuge Manager Steve Miller said he also thinks there was a design flaw.
“I think that there would always be water the day it was designed," he said.
The U.S. Fish and Wildlife Service, which manages the Kenai National Wildlife Refuge, provided additional funding for the project. But Miller said DOT had the say over the underpass design.
“Now we’re having to deal with water in that underpass for the first four weeks or so of use every spring," he said.
McCarthy said DOT considered drainage but didn’t anticipate the direct irrigation of the creek right to the foot of the underpass.
The Skyline underpass in particular was meant to make road crossing safer at the foot of one of the area’s most popular hikes. But hikers are back to scurrying across the road between the cars and trucks whizzing by.
“We just want to urge pedestrians to make sure they are safe when they do that crossing, especially as traffic starts to pick up in June and July," McCarthy said.
She said DOT hopes the pond dries out before then. Last year, it did around mid-May.
McCarthy said DOT’s working toward a solution to the problem.
“Our construction staff is going to be meeting and talking about the current situation, the design, what might be able to occur to get this water away from that undercrossing," she said.
The road project that created the underpass and others along the Sterling Highway is complete so DOT would have to look at other sources of funding.
“In the grand scheme of things, it’s a relatively inexpensive fix," she said.
There are other areas in the vicinity with new drainages after the fire. But McCarthy said this is the only spot with this sort of flooding.