Culvert operation

AuSABLE FORKS – The humble highway culvert – cheaper than a bridge and unseen by drivers tooling through stream-laced mountains – has become a focal point in efforts to help communities and wildlife adapt to climate change.

The critical role of the structures – essentially big pipes or concrete boxes carrying streams beneath roads – was demonstrated dramatically in a series of extreme weather events hitting the Northeast in recent years. In 2011, Hurricane Irene and Tropical Storm Lee washed out roads throughout mountains of New York and New England as culverts not designed for such enormous volumes of water were overwhelmed.

The planned rebuilding of aging or storm-damaged culverts is giving ecologists a rare opportunity to help wildlife expand their range into cooler regions to adapt to climate change by eliminating barriers imposed by highways and poorly designed culverts.

“We’ve been exploring using culverts as a way to alleviate flooding and protect human safety, as well as helping fish and wildlife,” said Connie Prickett of the Adirondack chapter of The Nature Conservancy. “It’s a big-bang-for-your-buck conservation strategy.”

New York’s Department of Transportation has incorporated into its project planning a simple computer tool developed by The Nature Conservancy to highlight areas where reconstruction will have the greatest benefit for wildlife.

“You can do a lot of research that ends up being a report on a shelf. That doesn’t help,” said Deborah Nelson, a state transportation official. “The information they’ve given us has been really helpful.”

Nelson said the Geographic Information System program developed by the conservancy’s Adirondack researchers identifies 149 culverts out of 1.2 million statewide as priority ones to replace with fish-friendly designs.

A well-designed culvert allows fish swimming upstream to pass through by ensuring the water flow isn’t too fast and there’s not a big drop from the culvert edge. A dry shelf may be added for wildlife such as bobcats.

When replacement is cost-prohibitive or impractical, the culvert might be made more hospitable to fish and the streambed more resistant to flood damage by installing large boulders to create a step-like structure in the stream at the downstream end of the culvert, said Michelle Brown, an Adirondack Nature Conservancy biologist.

New York’s transportation agency estimates that its $90 million annual cost of culvert maintenance and installation would be increased by as much as 80 percent if all stream crossings were rebuilt to ecological standards. The new tool identifying the most crucial sites makes the most of limited resources, Nelson said.

By adding climate change adaptation and fish and wildlife benefits to their highway projects, local and state agencies can stretch their highway budgets further by tapping into federal wildlife funds, said Corrie Miller, executive director of the AuSable River Association in the northeastern Adirondacks.

“The Fish and Wildlife Service is really interested in trout habitat, designing culverts so fish can move to cooler waters,” Prickett said. “They bring matching funds to communities.”

The federal agency noted that 81 culverts built in southern Alaska to improve salmon passage over the past decade survived last September’s 100-year flood in the region, while roads with older, undersized culverts were washed out.

This summer, New York’s Department of Transpor-tation will begin one of 19 pilot projects funded nationwide by the Federal Highway Administration to rebuild infrastructure to withstand severe weather events expected with climate change. The project is on a tributary of the AuSable River in the Essex County town of Jay, where an undersized culvert has caused severe erosion.

Helping wildlife move around to adapt to climate change goes beyond culverts. Mark Anderson, based in Boston, leads a Nature Conservancy team that assembled data on species distributions, river barriers and land ownership patterns across 13 states in the Northeast and mid-Atlantic. The goal is to provide land and water connections so wildlife can more readily move northward and to higher elevations, as they’ve begun to do in response to climate change.

The team developed computer tools that are being used by state and local officials throughout the northern forest region, Anderson said.

“Movement of fish and animals and plants has always been an important issue in conservation,” Anderson said. “They have breeding and foraging habitat in different places. But the climate change thing has really upped the ante.”

In the Northwest, a Seattle-based Nature Conservancy group has developed Linkage Mapper, a computer tool that automates wildlife habitat corridor mapping. Researchers are using it in a sage grouse habitat study in Washington and the Cascades Carnivore Connectivity Project.

“If a state or federal agency is looking at where to restore or protect habitat, it can now focus on routes that allow wildlife to easily access higher-elevation habitats,” said Brad McRae, a developer of the program.


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