Part 2: The Culvert Dilemma – April 2026
Gale K. Vick is a 57 year resident of Alaska with a long history of research and commentary on fisheries policy for various organizations.
Part 1 of this series on the Ambler Road challenges to wild salmon identified some general concerns about salmon survivability within a major construction/utilization project. Part 2 is a brief overview of the specific problems that culverts represent.
Culverts are those road crossing under-structures that few of us ever think about. “Compared with dams culverts have historically escaped public attention; most people drive over them every day without noticing. “I used to tell people I assess culverts,” recalls Mark Eisenman, a planner at the Alaska Department of Transportation. “They’d say, ‘What the hell’s a culvert?’”[i]
I had my own culvert epiphany when I was on the Board of the Tanana Valley Watershed Association involved in the lower Chena River / Cripple Creek culvert renovation designed to increase historic fish passage.[ii] It was a massive undertaking of millions of dollars. But then the upper Chena River culverts caught my attention with their aging “pipes.” In conversations with many fisheries scientists, I started learning about the supreme importance of culverts to the in-migration of spawning salmon and out-migration of salmon smolt. Dr. Erik Schoen (UAF/CFOS) sent me photos of Chinook yearling smolt that were trapped from going downstream by unmonitored debris in a culvert. Then I saw a U.S. Fish and Wildlife Service article visually showing salmon unable to navigate poorly designed culverts.[iii] That discovery opened up an entire inquiry which was expanded when I commented on the Ambler Road SEIS and began reading a staggering number of papers on culvert design, costs and impacts.
Culvert design, installation and maintenance over time are absolute factors in anadromous species passage and yet the discussion is often neglected or an afterthought when designing projects that cross anadromous streams. Even in Alaska, a state with few road systems, aging or poorly designed culverts over stream crossings are barriers to declining salmon populations. The true cost of maintenance, assessment, replacement is in the billions of dollars. It boggles my mind to think how the Ambler Road project would multiply that problem.
Insufficient culvert design and maintenance are hidden killers for wild salmon. “Migrating salmon depend on accessible waterways. Young salmon need to reach the ocean where there is space to disperse and much more abundant high-energy food than in fresh water in order to mature and grow to large sizes. Culverts (tunnels that carry a stream under a road) can be barriers to fish migration when they are too small or steep or are perched too high to allow fish to pass.”[iv]
Poorly designed, under-maintained, undersized, or aged culverts create impassable barriers, restricting access to crucial spawning and rearing habitats. Key issues and impacts include:
- Physical Barriers: Perched culverts (outlets above the stream bed) are often 100% impassable to migrating adults. Culverts clogged by debris. Culverts that are crushed or moved over time by melting permafrost or other factors
- High-Velocity Flows: Undersized pipes act like fire hoses, creating high-velocity environments that exhaust juvenile and adult salmon attempting to migrate, essentially blocking their pathway.
- Habitat Fragmentation: Thousands of miles of potential spawning streams are cut off by poor structures, significantly impacting wild populations by blocking access to crucial habitat for feeding, spawning and rearing, reducing channel complexity needed for rearing
- Disruption of natural stream processes, leading to habitat degradation and restricting movement for aquatic species, holding back streambed sediment needed to replenish streambed downstream
- Reduced Populations: Removing or replacing “red pipes”[v] culverts with fish-friendly designs, like bridges, is identified as a critical action to boost salmon populations.
- Ineffective maintenance: Culverts in salmon bearing streams may act as a chief “barrier” to salmon if not maintained, summer and winter. Some species of salmon spawn well into late fall and under the ice. Salmon alevin[vi]and juvenile habitat need protection in all seasons.
“For nearly 25 years, the Alaska Department of Fish and Game (ADF&G) had recognized this issue and in 1999, ADF&G created the Fish Passage Improvement Program to begin assessing culverts around state roads. Today, the Fish Passage Program, which is part of Sport Fish, continues to assess culverts but also provides technical expertise and other assistance to fish passage projects around the state. The information is used by restoration groups planning replacement projects, by road managers planning road upgrades and for watershed assessments and other decision-making tools.”[vii] But this is just a tool to identify fish passage needs on stream crossings in the Anadromous Waters Catalog (AWC) which is estimated to have only identify 50% of Alaska’s streams, many still unidentified in the Ambler Road project area.
The Ambler Road Project will have culverts in the thousands crossing fish streams. Who is going to monitor those culverts on a seasonal basis and who is going to be responsible for repair, clean up, replacement over time? While agencies may be passing the ball or wrangling over this responsibility, significant numbers of salmon could be extirpated in the process.
Here is the reality: Alaska has limited financial, technical and manpower resources in achieving the level of protection regulations suggest. And often we do not have the political will. Laws and regulations are pre-empted all the time. Our state and federal agencies already do not have the financial and technical resources they need to address the current crisis, much less take on new tasks of monitoring thousands of remote site stream crossings. And then still not being able to do much about it. When you plunk a major construction or mining activity in the middle of a pristine wilderness you can expect that very little of what goes into a permit will actually result in the mitigation the permit was based on. Most of us who have been involved in any kind of major project development in Alaska can testify to this if we are honest.
The Amber Road Project is a 211-mile industrial road from the Dalton Highway to Alaska’s remote Ambler Mining District. The route crosses state lands (61%), Native corporation lands (16%), and federal lands (23%) managed by the BLM and the National Park Service. The first 19 miles of the road will be on BLM-managed public lands within the Dalton Highway Utility Corridor. https://eplanning.blm.gov/Project-Home/?id=9ba0fa87-a7f2-f011-8407-001dd803d067
References:
[i] Saving Migratory Fish, One Culvert at a Time : Millions of barriers underlie American roadways, blocking the passage of fish. The US is working to fix them .By Ben Goldfarb April 1, 2024 https://reasonstobecheerful.world/saving-migratory-fish-one-culvert-at-a-time/#:~:text=Compared%20with%20dams%2C%20however%2C%20culverts,to%20save%20sea%2Drun%20fish?
[ii] A journey to restore the historic habitat of Fairbanks’ Chinook salmon , Grace Veenstra February 20, 2025 https://storymaps.arcgis.com/stories/c21293729da34c82aa2f118e7c9c2670/print
[iii] Fish-friendly roads? Yes, that’s a thing. U.S.Fish&Wildlife Alaska June 13, 2017 https://medium.com/usfws/fish-friendly-roads-yes-thats-a-thing-d3da81e179f8
[iv] Salmon need better infrastructure, too / Aging culverts block salmon migration between freshwater streams and the Pacific Ocean. Ashlee Abrantes Analysis Nov. 24, 2021 High Country News
[v] “Red pipes” describe culverts that are not fish-passage safe, whereas “green pipes” describe culverts that are assessed to be fish friendly
[vi] The salmon embryo inside an egg hatches out to become an alevin (the A is pronounced AY as in play or AH as in cat). Wiggling energetically and releasing a little enzyme from its head, the embryo breaks through the egg membrane.
[vii] https://www.adfg.alaska.gov/index.cfm?adfg=fishpassage.database