When it comes to snorkeling, Spring Creek is a one-eyeball-at-a-time kind of place.
On this recent morning, Brian Riggers is attracting a few startled stares as he snorkels his way up the nearly dry creek bed. Clad head to toe in a well-worn blue wetsuit, the Lolo National Forest fisheries biologist is hoping to glimpse a trout just off the popular main trail in Missoula's Rattlesnake Recreation Area.
“It's kind of like looking through a periscope,” Riggers says as he edges upstream on hands and knees. “You look up into the channels and chutesŠit's a whole different world when you get down on the same level with the fish.
“It's also a lot more fun when there's more water than this. This is kind of hard on the knees.”
As Riggers carefully picks his way over rocks and debris, it certainly doesn't appear that stealth has anything to do with this approach to fisheries biology.
“Fish usually face upstream,” Riggers said. “If you swim up behind them, they see you, but they're not at all scared. I can usually get within about six inches before they'll bolt, as long as I move slow and don't splash too much.
“I've sat in a pool and watched cutthroats feed for hours,” he said. “It's amazing what you can learn when you put yourself at the same level as the fish.”
Two hikers stop to watch, shaking their heads with disbelief. There can't be any fish in that little bit of water, they announce before ambling off.
“There's a little cutthroat right there,” Riggers says moments later after water spews from his snorkel's top. “People walk over this bridge all the time and I bet hardly any believe there's any fish in here.”
After spotting a handful of other tiny little cutthroat, Riggers finds the prize - a 3-inch bull trout lying motionless against a mottled rock in the shade of a nearby willow bush.
“So in about 20 meters, I saw one bull trout and probably a dozen cutthroat in a stream that most people probably would say there can't be anything there.”
Riggers isn't surprised that people have a hard time believing there's native trout lurking in little trickles like this.
A few years back, biologists harbored their own doubts about many of the small tributaries scattered across western Montana.
The Forest Service had been busy replacing undersized culverts to give fish a better chance of navigating their way into the smaller creeks, but no one knew for sure just how successful those efforts had been.
“Most of the tributaries we were addressing with new culverts were very small - maybe two to four feet wide,” Riggers said. “Most people would probably have thought they didn't contribute much to our fish populations, even people who know fish pretty well.”
So back in 1998, Riggers and a few others pulled on their wetsuits and took a look. What their underwater explorations found was surprising.
Of the 17 small streams sampled, biologist found native bull trout in 14.
“That changed the thinking on what streams bull trout will use,” Riggers said. “I think most streams had bull trout at one time before this latest big drought.”
With this year's high temperatures and low water levels, Riggers decided this summer was a good year to revisit those same streams to see how native fish are faring.
“The conditions fish face this year are really limiting,” he said. “I wanted to see if those populations were hanging on or were just simply gone.”
Riggers found bull trout in four of the five of the streams he's snorkeled so far this summer.
In Six Mile Creek, bull trout have disappeared after apparently being pushed aside by invasive brook trout.
“Native cutthroat and bull trout require high-quality, pristine habitat,” Riggers said. “When it's not there, they can be displaced by non-natives like brook trout. Brook trout are just better adapted to live in degraded habitats.”
The good news is that he's found native trout in the other four streams.
With water temperatures soaring this summer, Riggers believes the tiny tributaries can be the perfect refuge for native fish. The small streams are as much as three degrees cooler than nearby rivers.
“They may not stay in the tributaries for long,” he said. “In some cases, they might even just come here to escape the heat of the day and then swim back into larger rivers to feed.”
That feat might not have even been possible before the Lolo National Forest replaced upwards of 200 undersized culverts.
In the spring, undersized culverts act almost like a fire hose when the creeks are running full. Even the strongest swimmers have a hard time blasting their way through to the other end.
The additional velocity pouring out the downstream side often scours out a pool. When the waters drop towards summer, the culvert can be left hanging above the creek channel which can create an impossible barrier to fish passage.The Forest Service has been replacing undersized culverts with more fish-friendly structures, include much larger culverts complete with substrate-lined bottoms that help break up the current's velocity and gives fish a chance to migrate upstream.
There's still lots of work that needs to be done.
On the Lolo National Forest alone, officials have identified about 700 fish barriers. Most of those are undersized culverts.
“Most streams go through private lands before they reach the river,” Riggers said. “That doesn't include any barriers off the national forest.”
The barriers that remain in place now fragment native trout populations, which make each one vulnerable. Every time a barrier is removed, those fragmented populations have a chance to interact with others, which dramatically increases their chance for survival.
“I'd much rather have a population of 100 fish than four separate populations of 25,” he said.
Replacing culverts isn't cheap.
An average culvert replacement project runs about $50,000. Riggers' entire annual budget for fishery-improvement projects on the Lolo National Forest is about $40,000.
Partnerships and stewardship projects have been paying the lion's share of the bills on culvert-replacement projects over the last few years, Riggers said.
Under the terms of a stewardship project, the Forest Service can use timber sales receipts to pay for restoration projects, like replacing a culvert.
“I think it's a good way of doing business,” Riggers said. “We're able to accomplish some fuel reduction work on the forest that our silvaculturist says needs to be done and we end up with some money to pay for these really expensive projects.”
Partners like Montana Trout and Trout Unlimited have also stepped forward to help raise money and acquire grants to fund other work.
“There are so many grant opportunities out there,” he said. “All we need are people willing to work with us. It's nice to work in the Missoula area where there are so many people interested in helping out.”
Reporter Perry Backus can be reached at 523-5259 or at pbackus@missoulian.com
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