Under rural roads throughout the Ausable watershed, streams are routed through plastic, steel, or concrete structures often significantly narrower than the width of the streams at normal flow. Undersized, collapsed, or poorly designed road crossings fragment natural stream pattern and ecosystems, contribute to erosion, and exacerbate flooding. They block native fish and other aquatic organisms from moving upstream to the cooler waters and habitat they need to survive and reproduce. High flows forced through undersized culvert pipes or bridges increase water velocities, eroding the bed and banks at their outlets, and in some cases, creating large drop-offs to the streams below.
Debris builds up quickly at the upstream ends of undersized culvert pipes, backing up natural flows, flooding roads, and requiring ongoing maintenance by local road crews. Undersized bridges may allow the passage of most debris, but still back up flows, impounding water upstream, eroding banks and widening the channel. Streambanks at either end of undersized road crossings are often eroded. Stripped of plants and the root systems that stabilize them, the banks collapse, adding more sediment and compromising the habitat of fish and other wildlife essential to a healthy stream. It is a vicious cycle. The good news is that these problems can be solved.
AsRA is improving transportation infrastructure in the Ausable watershed, increasing its resilience to the impacts of climate change. We are working with several partners to retrofit or replace culverts that block fish passage and exacerbate flood damage to local roads and private property. Our goals are to improve stream connectivity, fish habitat, and community resilience to flooding through the redesign and replacement of undersized culverts.
We're tackling the highest priority culverts, working side-by-side with town and county road crews. Our goal is to build a template for construction of smaller culvert replacements (under 20’ wide) that allows more towns to replace more culverts as funding becomes available. Upfront costs of a culvert replacement are significant, $150,000 or more, but the trade-off is little to no maintenance and reduced repair costs for the 70-year life span of the new structure – a significant savings for many towns.
What You Can Do
Spread the word. Talk to your community leaders about improving road crossings in your community. Take the time to visit the improved crossings found on the map above. If you have questions, contact AsRA. If you like what you see, thank your town and county leaders for building smart in your community.
Join AsRA! Staying informed is the best way to follow this issue and to support better culverts in your community and throughout the Ausable watershed.