BARTOW — Little by little, native brook trout in West Virginia’s Monongahela National Forest are regaining access to their former spawning grounds.
Dozens of prime spawning areas had been cut off by road culverts. By digging out the culverts and replacing them with bridges, work crews have significantly increased the amount of available spawning habitat in the upper Greenbrier River watershed.
“This one went in last year,” said Chad Landress, standing on one of the bridges’ decks and pointing upstream to a series of small pools, each no more than 3 feet wide. “Within a month and a half, we came back and found 7- to 9-inch trout spawning right up there.”
Landress, the Monongahela’s fisheries biologist, said the bridge replaced a small culvert that once allowed the tiny tributary to pass under a U.S. Forest Service road.
“The culvert had become ‘perched,’” he explained. “The culvert was too small, and when we got heavy rains and high flows, it concentrated the tributary’s flow and shot it out the other side like a fire hose. Over time, those fire-hose flows scoured out the stream bed downstream and caused it to drop away from the lip of the culvert. What we ended up with was a man-made waterfall that created a barrier to trout trying to get upstream to spawn.”
Dave Thorne, the West Virginia Division of Natural Resources’ trout biologist, said the speed with which trout are recolonizing their former spawning grounds is eye-opening.
“What’s really surprising is the numbers [of trout] a single bridge like this can generate,” he added. “Even in a tiny stream like this, a single pair of spawning brook trout can produce dozens to hundreds of young-of-the-year trout the very first year after recolonization.
“The lack of spawning habitat [for brook trout in the upper Greenbrier] has been a limiting factor. Every time we replace a [perched] culvert with something that restores a natural stream bed, we regain a little more habitat.”
Thorne said the culvert replacement has created “a pretty remarkable dynamic. We’re seeing fish grow faster and produce more young trout for the entire system.”
Digging up a perched culvert is the easy part; the hard part is replacing it with an equally durable structure. Sometimes prefabricated bridges are the answer; at other times, an arch-like “bottomless culvert” is the ticket.
The key, Landress said, is what workers do under those bridges and bottomless culverts. “You have to reconstruct a natural stream bed that allows [insects, crayfish and trout] to move upstream and downstream whenever they need to,” he explained.
Culvert replacement isn’t the only component to the Forest Service’s attempt to improve trout fishing in the upper Greenbrier. Mike Owen, the forest’s aquatic ecologist, said it’s one prong of four-pronged approach.
“It’s part of a watershed restoration action plan. We identified conditions that were impairing the quality of the aquatic ecosystem and came up with a plan to address those conditions,” Owen added.
One problem was sediment pouring into streams from the Forest Service’s extensive network of dirt-and-gravel-surfaced roads.
“As part of our study, we identified what roads we needed and had the funding to maintain, and other roads that we either didn’t need or couldn’t maintain,” Owen said. “We identified treatments for those. Most of the treatments involved ‘de-commissioning’ the roads, which involves un-building them and putting them back to a more natural condition.”
Forest Service officials also took a hard look at sections of stream that had become too warm for brook trout because the tree canopy had been removed.
“We’ve been working real hard to get trees planted in those areas so the streams are shaded,” Owen said. “As those trees grow, we also get the benefit of the root structures to help stabilize soils in the flood plain. And long-term, those trees provide woody material and nutrients for the streams themselves.”
Where the streams lacked pools and hiding places for trout, the Forest Service plan called for the introduction of so-called “large woody material” — logs and tree-root balls strategically placed and anchored to create better fish habitat.
“In this watershed, large woody material has been the primary source of habitat,” Landress explained. “It slows the water down, which allows sediment to settle out. It also creates and traps organic material, and it provides micro-habitats for young fish as well as adults. Essentially, we’re re-creating fish habitat so we can re-create the brook-trout fishery this watershed used to have.”
The Forest Service is picking up the tab for the work, which is now in its third year. Crews employed by Trout Unlimited, a national trout-conservation organization, are carrying out the work under Forest Service supervision.
Gary Berti, director of TU’s Eastern Home Rivers Initiative, totaled up the scope of the project so far:
“We started off with one project, which was to put in some large woody material in the East Fork of the Greenbrier at Island Campground,” he said. “That since has expanded into close to 50 miles of in-stream habitat improvement using woody material. We’re also doing the road-obliteration work, which amounts to more than 50 miles so far with another 30 to be done this year. In the Big Mountain area [on the Potomac River watershed], we’ve identified 100-plus miles of stream for work and the same amount of road for obliteration.
“This has gone from what we thought would be a one-off project to a landscape-scale restoration effort. It also has become a model for a lot of agencies, particularly in the East. People are coming from all over the country to take a look at the work we’ve done.”