Organizations combine efforts for salmon

MAT-SU -- Juvenile coho salmon now have a whole new world to explore in an unnamed creek that runs under Settlement Avenue in the Bogard Road service area. No, it's not a flood or a rerouting of the creek, but a new culvert, partially courtesy of Local Road Service Area No. 25.

"The water velocity in the old culvert was too high for juvenile salmon," said Matt LaCroix, a habitat biologist for the Department of Natural Resources Office of Habitat Management and Permitting. "The salmon couldn't get to the protected habitat perfect for rearing and wintering."

The culvert at Settlement Avenue previously was a 4-foot wide circular pipe, which, over the years, had caused scouring at the pipe's edge, causing a 4-foot perch that the smaller salmon could not jump. Even if the juveniles were able to jump the perch, the pipe was too small for the stream, so the water funneled in at a faster rate, making the water velocity to high for the salmon to swim up.

"When you have both of those together, it's pretty hard for fish to move upstream," LaCroix said. "We were ending up with a high winter mortality, which reduced the adult production rate."

When project manager for the Matanuska-Susitna Borough Public Works Department Chuck Kaucic started looking at replacing the culvert along the unnamed feeder stream for Cornelius Lake, he knew he was going to need some help.

"We don't know fish passage, but there are others that do," he said.

Kaucic worked with DNR, the U.S. Fish and Wildlife Service and the U.S. Department of Agriculture Natural Resource Conservation Service to come up with a plan of action to replace a number of culverts inside the borough. Settlement Avenue is the second culvert that has been replaced with this new team; there are at least six more crossings planned for the next few years.

"It helps the fishery and of course it helps the road system too," Kaucic said.

Besides the salmon problem at Settlement Avenue, the prior pipe was too small for the stream in general, causing an oxbow at one side of the stream and a massive pool of water at the other. Erosion from the road was starting to block the pipe's ends, and with plans to pave Settlement Avenue, Kaucic said he knew it was time to get in touch with agencies that could help.

"You shouldn't go out and build a job unless you know all the components," Kaucic said.

A stream crossing is separated into three phases: design, construction and bio-remediation. Geotechnical engineer Mark Hansen, a private engineer contracted by the borough to do the job, did the stream crossing design. Hansen did a nationwide search for a similar stream crossing, and based the design on a crossing in California.

The omega-shaped culvert is designed so passage is invisible to the fish going up stream. The 10-foot-wide bottomless culvert protects the stream from being cut off by the road, while leaving the water level at the existing stream, simulating a natural channel. Job Corps construction students put the pipe together last year, and Kopperud Transportation Inc. laid in the pipe Friday.

USFWS granted the borough $45,000, NRCS granted the borough $25,000 and the local road service area allocated $30,000 for this project.

The next phase of the project is bio-remediation, when the road slopes will be stabilized with low-growing plants to keep the slope from sloughing off into the stream. NRCS will design the plan for the bio-remediation, and the work will be done in the spring, prior to the road paving.