If a culvert on your property sits along a township or county road, it's not just your drainage problem to solve however you'd like — there's a standard it needs to meet, and getting it wrong can mean redoing the work later or dealing with road damage down the line.
Why Road-Adjacent Culverts Are Different
A culvert tucked away on private property only has to handle water from that property. A culvert along a road right-of-way has to handle road runoff, ditch flow from upstream, and in some cases traffic load above it — which is why the Department of Transportation has specific requirements for how these are built, not just a general best practice.
What DOT Standard Actually Covers
- Slope — culverts need to be set at a precise grade so water actually flows through rather than pooling or backing up. A culvert installed flat, or at the wrong slope, won't function correctly even if the pipe itself is the right size.
- Sizing — the culvert has to be sized for the volume of water the ditch or waterway is expected to carry, not just whatever pipe happened to be on hand.
- Erosion control — erosion matting and rip rap around the inlet and outlet protect the culvert and surrounding ditch from washing out, especially during heavy rain or spring thaw when flow is highest.
- Depth and cover — enough soil and material over the culvert to handle the load above it, particularly if it's under a driveway or road approach.
A Real Example
On a recent project in Unity, WI, we lowered and replaced an existing culvert, widened the property's driveway, and ran precision ditching to DOT standard — including erosion matting and rip rap around the culvert itself. We documented the project through completion, including a follow-up visit to confirm how the finished work held up.
See the full project write-up →
Why This Matters If You're Planning Culvert Work
If your culvert sits along a public road, it's worth confirming with your township or county what standard applies before work begins — some municipalities have their own permit or inspection process for culvert work along a right-of-way. Getting it built to standard the first time avoids a second visit (or a disagreement with the township) later.
See our
Water Control & Drainage Solutions page, or call
(715) 613-0011 if you have a culvert project that needs to meet DOT standard.
