The culverts and bridges that carry streams and brooks under our roadways are important. The problem? Most of them are either outdated or poorly designed.
Fish or other animals moving upstream to find food or spawning pools hit a dead end when waters are low. And when traditional migration routes are blocked, it throws the entire natural cycle out of whack.
Fish-friendly culverts also protect against flooding and “catastrophic failure.”
When the water is low, they block fish and other animals from reaching upstream waters. And when the water is too high? This happens.
Culvert problems usually fall into three categories:
- “Perched” culverts are elevated above the river. Fish hit an impassable wall and fail to complete their migrations. Salamanders, turtles and even mammals leave the stream and try to cross the road, and often get hit by vehicles.
- Undersized culverts clog-up easily. On one side of the road, water pools up and causes flooding. Water pushes even more forcefully through the passage, resulting in structural damage, road washout and erosion. Eventually, an undersized culvert is likely to become a “perched” culvert (if it lasts that long).
- Shallow culverts often only let a fraction of an inch of water pass through – not enough for most fish to navigate. Many have concrete or metal bottoms too, which deters animals from using them.
How big is the problem?
HVA has surveyed approximately 2,000 of the roughly 6,000 stream crossings in our watershed. Of those, 55% were barriers to fish and other aquatic wildlife, and 15% were expected to fail in a 25-year flood or less. Replacing (potentially) 2,000 culverts is a huge and costly undertaking for towns and taxpayers.
(Click to enlarge)
(Click to enlarge)
How are we fixing it?
- Surveying and monitoring culverts to identify the scope of the problem.
- Consulting with watershed states, cities and towns so they understand the issue and the risk. When new roads are built or repairs are made, we’re making sure they’re built correctly.
- Prioritizing the worst and most dangerous crossings, so that limited resources are focused, first, on the biggest problems.
- Finding funding through environmental grants that help supplement limited municipal budgets.
Learn more about our town-specific Road-Stream Crossing Management Plans here
Check out this completed project (2018) on the Churchill Brook in Pittsfield, Mass.
(Click to enlarge)
