Culverts can impede the movement of fish. But culverts also keep roads and driveways from washing away. In that vein, they have a place, but must be placed properly to avoid issues, according to Laura MacFarland from Trout Unlimited. MacFarland gave a presentation regarding road crossings and culverts at the recent Lakes Convention in Stevens Point. Her presentation was entitled, "Reconnecting Aquatic Ecosystems."
MacFarland spoke with the group about Trout Unlimited (TU) and the work they do as well as why Wisconsin's transportation infrastructure was important to the organization. She also talked about what lake organizations and other groups could do to help address aquatic barriers such as culverts.
Prior to three years ago, MacFarland said, TU did not have any staff in the Great Lakes basin. Now, thanks to the Great Lakes Restoration Initiative, they have been able to put staff on the ground in this region. Since 2014, she said, TU has been working to improve cold water fisheries in Wisconsin, predominantly in the Lake Michigan basis. Their focus has been reconnecting cold water habitat.
"We have been able to reconnect 42 miles of streams through 42 culvert replacements and abandonment of one culvert," she told the group.
One of the reasons this is important is for brook trout, Wisconsin's only native trout, throughout their lifecycle. They need to be able to move around and they need cold water, she said. Trout move seasonally, she said, to find the proper temperature water, sometimes moving up to 30 miles. They also move for spawning and rearing habitat.
Culverts, she said, are one of the main barriers to that movement. While many people think about dams as barriers to movement, culverts are the main barriers to movement in the midwest. Of particular concern are improperly placed culverts.
Culverts can form several types of barriers, according to MacFarland. There are jump, velocity, depth and exhaustion barriers. Each presents a different issue for fish and other species that need to move around during various parts of their life cycle. A jump barrier, just as it sounds, causes fish to have to jump up into a culvert placed too high. This can block movement of fish.
A velocity barrier constricts the flow and speeds up the velocity of the current, which can exclude at least some year classes of trout from traveling, she said. Depth barriers are culverts too shallow to allow for fish movement, and exhaustion barriers create a condition where certain species or ages of fish cannot sustain the necessary swimming speed to make it through the culvert. All of these barriers restrict fish movement and even movement of other species.
She also talked with the group about the economics of fish-friendly culverts. She said proper culverts can be more expensive, but they do also last longer. An undersized culvert, she said, normally last about 35 years, where the fish-friendly culverts they are installing now, last approximately 75 years.
Budgets for municipalities being what they are, especially smaller municipalities, it can be difficult to convince a municipality to put in the proper culvert. There is help, though, to augment resources for municipalities to address problematic culverts.
There are DNR river management grants. The Department of Agriculture, Trade and Consumer Protection (DATCP) has engineers to help with planning, as does the Natural Resources Conservation Services (NRCS). NRCS, she said, even had resources to help on private lands. She said municipalities, and even private entities or organizations should think creatively about who can help with costs associated with replacing culverts.
With an array of partners working together on a project, she said, those with an eye on conservation would be more likely to find success in getting projects completed with proper culvert placement, or help in determining whether or not a stream crossing would even be necessary, or if a travel way such as a private road, could be routed in such a way as to bypass the stream. Groups like TU, Mac Farland said, would be happy to help with assessments and to offer assistance in linking resources where possible.
Beckie Gaskill may be reached via email at email@example.com.