Main-land Development Consultants

5 Culvert Crossing Considerations

5 Culvert Crossing Considerations

Culverts are a little bit like cats. Sometimes they don’t seem to be doing anything. Then without notice, they’re a focus of rushing activity. They can be expensive and problematic. They need attention exactly when you’re busy with something else. Failing culverts can cause varying issues, from nuisance damage to attempted murder without notice. Culverts are the cats of infrastructure, only less cuddly.

When a culvert is failing, the temptation is to go back to the yard for a replacement culvert of the same size. But be careful! In today’s world, there’s more to it.


Drainage vs. Streams


Culverts come in two basic scenarios: those that convey a drainage and those that convey a stream.

A drainage is a water channel or swale that flows when it rains and drains from the road, ditch, and uphill areas. Most ditches are drainages. Drainage culverts should be sized appropriately and replaced in the normal manner. Timing is flexible.

A stream, on the other hand, is a natural resource regulated by federal, state, and some municipal authorities. Telling the difference isn’t so easy. Identifying streams is a scientific and regulated process involving five points of data and should be performed by a professional scientist. Worse, if a regulated stream enters a roadside ditch, flows along the ditch, then through a culvert, that could still be a stream culvert. Yes, sometimes ditches are considered regulatory streams. Worst, flowing water may not be part of the equation. It’s risky to assume about streams.

Stream culverts are regulated. Permits are required to replace a stream culvert and there are timing restrictions. Sizing a stream culvert is part of the permitting process, so whatever is back in the yard may not do. Stream culvert permitting includes review by:

Maine DEP through the Natural Resource Protection Act. Maine IF&W through DEP consult in the NRPA process. US Army Corp of Engineers, New England Division. U.S. Fish & Wildlife Service through USACE review process. Sometimes the local municipality has regulations.

If you’re not sure, let us know. We have professional scientists and engineers who understand streams and the permitting process.



If you have a stream culvert that’s in rough shape or failing, you may not need to go it alone. Maine DEP offers grants to municipalities for up to $95,000.

Grants are merit based on positive environmental impact. Main-Land can lend perspective on which crossing candidates should score highly. 
Depending on the location and flooding history, FEMA will sometimes step in with funding instead or in addition. Starting September 1, 2020, the DEP will make application materials available for the next round of grants, with submissions due on November 16, 2020. Award will be January 2021.

Not a grant writer? No problem. Main-Land has helped other Maine cities and towns successfully secure funds and navigate the design, bidding, and construction of these crossings.



Getting a culvert sized properly is critical to longevity and safety. But culvert capacity sizing is often not obvious. For pre-planning purposes use the following available info:

Current culvert size or larger is a good starting point. Don’t go smaller. Does the road crossing overtop or washout frequently? Make it bigger. Has there been development upstream? Proposed development? Make it bigger. For streams, use 1.2 times the bank-to-bank full width of the stream channel.

Publicly available crossing/watershed data:

Publicly available stream crossing habitat and barrier information:

Stream smart design techniques explained:

The crossing may warrant a stormwater model by a Main-Land engineer to properly size the culvert.



Catastrophic culvert failures never happen on a sunny Tuesday afternoon. No, like your cat, catastrophe happens at 3am on a Saturday during a hellish downpour.

Hopefully, the washout gets noticed before someone drives into the hole. Safety first. Secure the site so no one gets hurt. Don’t get too close. Undermined embankments, hidden sinkholes, and hanging pavement is common in these situations.

Main-Land is on alert during big storm events and can generally snap into action in an emergency culvert failure. Call: 
Main-Land office at 207-897-6752, 
Rick Dunton at 207-931-9909, or 
Bob Berry at 207-931-9931.

Emergency permitting provisions exist for both NRPA and USACE. A consult with the agency is good starting point. Some key contacts:

Land Enforcement (Division Director & Permitting Assistance Liaison) - Mark Stebbins 592-4810 
Augusta Region – Dawn Hallowell 557-2624 
Bangor Region – James Beyer 446-9026 
Portland Region – Alison Sirois 699-7028 
Presque Isle Region – Scott Belair 760-3145 
USACE Maine Project Office, 442 Civic Center Drive, Suite 350, Augusta, ME 04330, 207-623-8367



Lastly, the flat-tailed hydrologist causes culvert problems throughout Maine. Through no fault of your own, these dam rodents stop up culvert inlets, causing flooding and road damage. They join my wife’s cat as a nuisance animal.

In Maine, it’s a Class E crime to capture or kill a nuisance beaver, unless performed by the Maine IF&W. Removing their dam is also regulated. So, leave them alone and call the game warden. There is an open season on trapping beaver, however, so if the timing is right a trapper may get the job done. Even still, we recommend IF&W consultation.

Lastly, there are culvert entrance fence designs that slow down but may not stop the ingenious beaver. Call for details.

Culverts do the important job of transporting water and protecting our roads. Because water is concentrated in that spot, culverts represent a critical point in your road network.

Just like a cat, a culvert can present an immediate problem without warning. You’ll need more than a laser to avoid the problem. Call Main-Land for a free consult or to set up a site inspection.

Call right now: 207-897-6752, or visit for more information.

Written by Bob Berry and Rick Dunton.

Bob Berry is owner and CEO of Main-Land Development Consultants, a land use consulting company in Livermore Falls, Maine. He is a board member for Franklin Savings Bank and an author striving to help small business owners. See and for more information.

Rick Dunton is the Director of Engineering at Main-Land, and can be reached via email at


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