Culvert Assessment
Highest Priority Culverts to be Replaced
What's the connection between this
bad culvert, rotting salmon, and anglers?
Answer: This culvert blocked that fish from laying a thousand or more eggs, which hurts our local economy by reducing the number of happy anglers.
Culvert Assessments
A single road crossing with a bad culvert can prevent fish from reaching miles of habitat. Small tributaries provide the path to salmon nurseries. Juvenile salmon, particularly coho, migrate up streams. Studies have shown that juveniles that successfully migrate up and down small streams survive better in the ocean. It is important to keep these migration routes free of barriers.
What we look for...
In the field we evaluate how high the drop or “perch” is at the outlet. If it is greater than 4-inches, juvenile fish can’t make it up. If the slope of the culvert is too steep or the culvert is too narrow then the water flows too fast, also denying fish the ability to make it to their nurseries.
We have been assessing culverts across the entire Kenai Peninsula for the past 3 field seasons. By combining our results with previous surveys by Alaska Department of Fish & Game, a total of 517 stream crossings have been identified. Of these crossings, 270 are culverts crossing state cataloged salmon streams while the remaining are bridges, dams, weirs, or ATV trails. Of the 270 culverts assessed, a total of 48 (18%) provide adequate passage, 93 (34%) provide marginal passage, and 129 (48%) provide inadequate passage.