Native trout exhibiting remarkable response to fish ladder on Rattlesnake Creek
For the first time in a century, native cutthroat and bull trout are free to return to their historic spawning stream in the pristine headwaters of Rattlesnake Creek.
Since 1903, when Montana Power Co. built a dam on the creek to create a reservoir for Missoula's water supply, those native trout and other fish have been blocked from their spawning migrations.
This spring, a permanent fish ladder was constructed at the dam, now operated by Mountain Water Co., which provides a passage around the dam for native trout.
"It works great," said Ladd Knotek, a fisheries biologist for the Montana Department of Fish, Wildlife and Parks, who spearheaded the project that was the result of a collaboration of several agencies and organizations over the past two years.
A temporary test ladder that was installed in the spring of 2002 proved that the concept could work.
"We're just at the beginning of the cutthroat spawning run," said Knotek. "And we've already caught more cutthroats than all of last year. When we do river estimates on the Clark Fork River, we find up to 20 to 25 adult cutthroats per mile. We've already caught 80 adults at the dam this year. That equals the number from here to Kelly Island. So a significant number of cutthroats between here and the mouth of the Bitterroot are coming up to this stream."
Since the end of March when the fish ladder began operating, he said, an average of 10 to 15 fish a day have passed through it.
The fish ascend a series of 11 eight-inch steps in a gracefully curving channel that was sculpted into the bank on the east side of the creek about 100 feet below the dam. Then they swim about 100 feet through an underground culvert to the reservoir above the dam. A series of grates on the surface provide a light source for the fish to follow. The total length of the ladder is 160 feet.
Fish are attracted to the ladder by the strong flow from a second pipe that passes underground from the reservoir and empties into the stream at the entrance to the ladder.
At the up-stream end of the reservoir, the fish enter a trap, which biologists check daily. The biologists net all the fish, placing the native cutts and bull trout into the stream above the dam, where they can continue their migration to the critical spawning habitat in the upper 15 miles of the creek in the Rattlesnake Wilderness Area.
All nonnative fish, including rainbow and brown trout, are returned to the stream below the dam.
Rainbows and browns successfully spawn in the lower five miles of Rattlesnake below the dam, Knotek said. But the cutts and bull trout require the more specific habitat conditions that are found in the upper 15 miles above the dam.
"Based on water temperature and time of year," said Knotek, "we'll turn on the ladder in the spring when the cutthroats run, and continue operating it through September, to overlap the bull trout spawning run."
For the past two years, he said, between 30 and 40 migratory bull trout have shown up at the dam on their spawning migration.
Biologists manually transported some of those bull trout above the dam in the past two years. The result was a dramatic increase in spawning redds, or beds, counted in the upper stretches of Rattlesnake Creek.
"We're hoping to see a run of large proportions in about five years," Knotek said.
The project was a cooperative effort of Mountain Water Co., FWP, Missoula's Westslope Chapter of Trout Unlimited, the Forest Service and the federal Bureau of Reclamation, according to Knotek.
FWP's Future Fisheries Program contributed $67,000 to the project. The Bureau of Reclamation chipped in $40,000 in in-kind services, including the design expertise of engineer Jeff McLaughlin from Boise, Idaho. Other contributions included $25,000 from the Lolo National Forest, $30,000 from Smurfit-Stone Container and $20,000 from NorthWestern Energy.
Mountain Water has agreed to provide maintenance for the ladder.
"It's so cool, I'm speechless," said Bruce Farling, executive director of Montana Trout Unlimited. "In the 10 years I've been involved with Trout Unlimited, I've worked on 100 to 200 restoration projects in the state. I can't think of one that's going to have a more significant and measurable benefit to wild fish in Montana."
"And the best part," added Shane Hendrickson, a fisheries biologist for the Lolo National Forest, "is it's right in the back yard of town. This is probably the best project directly beneficial to fisheries that I've been involved with."
The fish ladder doesn't interfere with the operation of the dam, or its use as a backup to Mountain Water's system of wells that supply the city's water, according to John Kappes, assistant manager and vice president of the company.
The original dam built in 1903 was a wooden structure, Kappes said. It was replaced in 1924 with the current concrete dam. It was used as Missoula's sole water supply until 1935, when it was augmented with wells.
In 1983 giardia, a microscopic parasite, was discovered in the stream water and its use was discontinued. Now Mountain Water maintains the dam and reservoir as a "standby" water supply, according to Kappes. The company is studying the feasibility of bringing it back into use, he said.
"The Rattlesnake drainage has definitely been an incredible resource for the Missoula community for generations," Kappes said, "for a water source, the fishery, wildlife and recreation. This project provides a good example of how we can work with those different interests to protect this resource for future generations."
While historical records are a little murky about the origin of the name Rattlesnake Creek, Kappes said, records indicate the local Indian tribes had a name for it: "The Little Bull Trout."
Reporter Daryl Gadbow can be reached at 523-5264 or at firstname.lastname@example.org