“Yesterday or the day before, you would have seen cutthroat (trout) jumping up from pool to pool,” said Knotek, a fisheries biologist with the Montana Department of Fish, Wildlife and Parks. “With this cooler weather today, you won't see a one of them moving.”
Even so, what was visible at this site, located near the spillway of a dam owned by Mountain Water Co. just downstream from the main Rattlesnake National Recreation Area trailhead, was impressive: an artificial series of pools that stairstep around one side of the dam, fed by an underground culvert that draws water from the reservoir above, all of it designed to allow native bull trout and cutthroat to circumnavigate the dam that had previously blocked their upstream spawning migrations for 100 years.
“The year before this fish ladder was put in, we counted 12 redds upstream,” said Knotek, referring to the gravel beds cleared out in the streambed by bull trout in preparation for spawning. “Now we're seeing 35 to 40 redds up there. And the fish that hatched the year that we began this project are just now getting to spawning age, so we're hoping to see a significant spike in the population in the next couple of years.”
That's good news for bull trout, which are currently on the federal endangered species list. It's the kind of good news that gives hope to Derek Goldman, Montana field organizer with the Endangered Species Coalition, a Washington, D.C.-based nonprofit that aims to build awareness around endangered species issues.
“This (fish ladder) is a great example of the kind of successful work that's going on around the country to protect endangered species,” said Goldman.
Goldman organized Saturday's tour of the Rattlesnake Creek fish ladder in conjunction with the second annual Endangered Species Day, a federally proclaimed day aimed at building recognition and understanding about the importance of protecting rare, threatened and endangered animal and plant species.
Although Endangered Species Day was technically Friday, Saturday morning seemed a better day to get people out to see the fish ladder, Goldman said .
“This project has been really successful in making it possible for the bull trout to get upstream and spawn,” Goldman said. “It's something that really should be celebrated.”
A small crowd of about 15 people participated in Saturday's tour of the site, which is normally closed to the public. The dam and reservoir are still privately owned by Mountain Water Co., which maintains the reservoir as a backup water supply for Missoula.
The fish ladder only carries water for approximately three months out of the year, during the spawning migrations of bull trout and cutthroat trout. During other parts of the year it is shut down, to block other species of fish from migrating up the stream.
Fish ascend the ladder by moving up a series of 11 eight-inch steps separated by deep pools. They are attracted to the ladder by the strong, cold flow created by a second pipe that passes underground from the reservoir and empties into the creek next to the entrance to the fish ladder.
According to Knotek, studies indicate 80 percent to
90 percent of cutthroat that migrate up to the dam from the Clark Fork River and lower reaches of Rattlesnake Creek manage to use the fish ladder.
Only about half of the bull trout that migrate up to the dam end up using the fish ladder. So once a year, Mountain Water opens the gate of the dam itself, allowing a free flow through the dam.
“That has gotten us to a point where we're getting pretty much 100 percent of the bull trout up past the dam,” said Knotek.
Despite the success of the project in increasing migration up the creek, Knotek said bull trout populations as a whole remain in a precarious position due to habitat degradation, drought and fishing pressure.
“Bull trout are in serious trouble still,” Knotek told the assembled throng on Saturday. “Through this project, I'm just hoping they can persist in the creek.”
Reporter Joe Nickell can be reached at 523-5358 or at jnickell@missoulian.com
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