Culverts provide an abundance of benefits to us every day. They allow us to pass over water, and for fish and wildlife to pass beneath us. And they allow us to go about our daily lives and ideally, for fish and wildlife to do the same. But when they’re badly designed, the results can be disastrous for people, communities, and the environment.
Between 2008 and 2015 U.S. Forest Service partnered with more than 200 organizations in the Legacy Roads and Trails Program, which replaced more than 1,000 culverts across the U.S. The aim of the program was to upgrade culverts to emulate natural streams, and to allow fish and wildlife to pass more naturally both upstream and downstream. These culverts are called stream simulation culverts and consist of an arch above an open bottom, allowing the stream to continue beneath as if the culvert was not there at all.
Badly designed culverts come with a host of problems. They can cause devastating infrastructure property and infrastructure damage if they become blocked with debris or become overwhelmed with water.
Beyond the human cost, they can have a profound effect on the health of the watershed and the fish and wildlife that depend upon them. Badly designed or badly maintained culverts can cause bank slumping, erosion, and scouring—severely degrading water quality and habitat. Worse yet, the consequences of bad culvert design don’t stay localized.
“What happens upstream, affects everything downstream,” said Nathaniel Gillespie, Assistant Fisheries Program Manager at the U.S. Forest Service.
Streams, like all waterways, are complex ecosystems. Streams flow into and out of one another, affecting their surrounding environments, and the fish and wildlife that depend on them.
“Fish depend on a sizeable enough habitat to live and grow,” said Gillespie, “but they also depend on access to other bodies of water to breed and thrive.”
Gillespie said when that travel is restricted, it can effect fish populations and restrict the size of the fish living in the waterways. Countless rural communities around the country depend on the $10 billion spent every year in and around National Forests and Grasslands. Much of the appeal in these areas can be attributed to clean, abundant water and healthy fish and wildlife.
Because water systems are so interconnected, and because of the cascading effect of badly designed culverts, the role of well-designed culverts becomes clear.
“The Forest Service made this investment with our partners because these communities and our nation are going to reap so many benefits from it,” Gillespie said.
“With safety, environmental and economic benefits of smart culvert design, good culverts are just good sense.”