Floods draw more attention to culverts

Posted: Tuesday, November 12, 2002

When last month's flooding washed out sections of Kenai Peninsula roads, many area residents found themselves isolated and stranded -- much like juvenile salmon can be cut off from their homes by impassable highway culverts.

The flooding heightened awareness of a growing concern among some who believe culverts across the state don't adequately protect anadromous fish populations.

That may soon change, as state agencies are beginning to work together to ensure both humans and fish are able to move freely through their respective transportation corridors.

Alaska's departments of Fish and Game and Transportation and Public Facilities recently signed a joint memorandum of agreement on how culverts are designed, permitted and constructed statewide. The purpose of the agreement is to ensure fish -- especially salmon -- are taken into account whenever and wherever culverts are put in place.

The move is needed because some culverts have been shown to have a harmful impact on the migration of juvenile salmon between feeding and wintering areas. According to Robert Ruffner, executive director of the Kenai Watershed Forum, many culverts need to be replaced or redesigned to address the problem.

"If a culvert prevents a juvenile fish from swimming upstream, it is a significant concern for habitat fragmentation," Ruffner said.

The recent flooding might provide the state with a reason to move forward more quickly to redesign some culverts, which Ruffner said are often too small. An undersized culvert can present numerous problems for juvenile salmon, from water pressure being too high when water flow is heavy, to the culverts becoming clogged with debris. Now that several of the problem culverts have been destroyed, Ruffner said the state has an opportunity to reevaluate how its culverts are designed.

"It's a good opportunity to go back and do these things correctly," he said. "Now's a really good opportunity to go back in and fix some of these things right."

That should be easier, now that state agencies are working cooperatively to take into account fish passage beneath roadways. Fish and Game recently completed field work on a study that will be used to pinpoint the exact fish passage concerns for all state-maintained culverts. That study will be forwarded to DOT, where it will be used in future planning decisions.

According to Fish and Game habitat biologist Steve Albert in Anchorage, the study will enable both departments to understand the exact issues involved at specific streams.

"The purpose of the project was to determine the extent of fish passage problems by completing a peninsulawide culvert inventory on state roads, assessing those culverts for fish passage, and then prioritizing any barrier culverts for future restoration work," Albert said.

The study should go a long way toward helping DOT understand fish passage issues when it works with culverts.

"In the past, they've gone in predominantly to move water beneath the roadway," Albert said. "We want to be able to move fish along with the water."

Some ways to improve fish passage might include using alternative culvert designs, such as "bottomless arch" culverts; replacing culverts with bridges; or installing larger culverts.

However, fixing potential problems might not be as easy as getting state agencies on the same page. Funding issues will be a major concern as individual culverts are evaluated, and culverts don't usually come cheap.

"They're very expensive to fix," Ruffner said.

However, he said he hopes the public and state government will place a high priority on making sure culverts are adequate for the needs of both human and aquatic life -- especially in light of the recent floods.

"Undersized culverts are not only a problem for fish. There's also a concern for human life," he said, noting that some of the damage from last month's flooding may have been the result of clogged or undersized culverts.

"People sometimes have a short memory with these things," Ruffner said. "Hopefully, people will remember."

Subscribe to Peninsula Clarion

Trending this week:


© 2018. All Rights Reserved. | Contact Us