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Water and wood
Ernie McKenzie, fisheries biologist for the U.S. Bureau of Land Management, jumps from log to log across Belmont Creek. The wood provides a more complex habitat for cutthroat and bull trout. The flagging marks a spawning redd of a westslope cutthroat trout.
Photo by KURT WILSON/Missoulian

Natural recipe brings life to fish habitat in area streams

BELMONT CREEK - Only nature knows the magic formula.

So Jo Christensen provides the raw materials and stands back - in awe - as Belmont Creek comes calling on the meadow not far from its confluence with the Blackfoot River.

As water meets wood.

A year ago, with help from a pair of 1,900-pound Belgian draft horses, Christensen dropped 70 pieces of wood - whole trees - into this reach of Belmont Creek.

Without wood, water cannot provide trout with the diversity of habitats they need to make it through life. Sometimes, wood slows a stream's descent. Other times, water speeds up to get around the obstacle. Each time, the combination of wood and water makes a place favored by fish.

"Wood will turn water in 50 different directions, creating all kinds of different habitat conditions - different depths, different gradients, different flows," said Christensen, a fisheries biologist for the U.S. Bureau of Land Management. "Fish need that complexity."

When trout are spawning, they need shallow, fast-moving water. When they are baby fish, they need slow water. When they are old fish, they need deep, complex pools where they can hide from predators. When the water's high, they need quiet, off-channel areas.

"Slow water to rear and rest, fast water to spawn and feed," Christensen explained. "What we want to see in a stream is all kinds of water speeds and water depths, and lots of different size categories of rocks, and lots of organic material."

But streams throughout the West have been stripped of woody debris over the past century, as farmers - like the one who homesteaded the Belmont Creek meadow - replaced riparian areas with hay fields and confined streams to unnaturally straight channels.

Logging, subdivision and grazing added to the troubles, robbing hundreds of stream reaches of the trees and logjams that once provided habitat for native cutthroat and bull trout.

Then along came Christensen.

First at Chamberlain Creek, another Blackfoot River tributary, and now at Belmont Creek, she scavenged ponderosa pines and Douglas firs from loggers and deposited them in the water. The gratification, she likes to say, was instant.

"I never expected the response we got," Christensen said one afternoon last week, as she and a pair of co-workers counted the spawning redds in Belmont Creek.

Last year, there were no redds. "Zero," she said, "and the year before and the year before and the year before."

So far this spring, there are 58 redds.

Marked with orange flagging tied to streamside willows, the spawning beds are the work of fluvial westslope cutthroat trout, the rarest form of a rare species that migrates to the Blackfoot River during adulthood, then returns to the natal stream to spawn.

"Before, this reach of the creek was deep, narrow and composed of big, grapefruit-sized rocks - far too large for trout to spawn in," Christensen said. "It was the kind of habitat that humans would call boring."

"And that fish would too," chimed in Ernie McKenzie, also a BLM fisheries biologist.

Now, after just one rush of high water down Belmont Creek, the channel is changing. "There's a lot going on," McKenzie said. "It's pretty amazing."

As the creek came upon the logs, it dropped gravel of varying sizes - including the not-too-big, not-too-little size that trout use to create spawning redds. Too big and the eggs are crushed. Too small and the fry will suffocate.

"It's a little like Goldilocks," Christensen said. "Trout keep looking until they find gravel that's just right. They are really particular."

So particular, in fact, that Christensen doesn't even try to guess at the "magic formula." Nature, she said, is "perfectly capable of doing that work. We just need to provide the raw materials."

Before the project, 5 percent of this reach of Belmont Creek - about 1,700 feet as it flows through the meadow - was comprised of gravel suitable for spawning. Last week, 45 percent of the reach was comprised of spawning gravels.

Of most interest to BLM biologists are westslope cutthroat and bull trout, both of which are rare, both of which need complexity in their habitats, both of which will likely benefit from the Belmont Creek restoration.

This spring, the spawning redds were created by cutthroat - McKenzie and Christensen saw several of them at work in the gravel - and rainbow trout. In the fall, they'll watch for the big bull trout.

Westslope cutthroat trout have three possible life forms: adfluvial (which migrate to lakes), fluvial (which migrate to rivers) and resident (which stay in their natal streams). All three forms spawn in tributaries like Belmont Creek, always in the spring when water temperatures are about 10 degrees Celsius and flows are high.

Typically, cutthroat trout don't spawn until they are 4 or 5 years old. Few survive to spawn a second spring. Fry emerge between late June and mid-July, and spend anywhere from one to four years in their birth streams. Then they move into the big mainstem rivers and grow to maturity.

Woody debris is important, too, to the aquatic insects that provide food for the fish. Westslope cutthroat trout primarily eat insects and zooplankton, and do not grow very large - usually between 6 and 12 inches, according to Beth Gardner, a fisheries biologist for the Flathead National Forest's Swan Lake Ranger Station.

If there is no slow-moving water in a stream, all the leaves flush out in the fall and the insects have nothing to nibble on over the winter, Christensen said. "In order to retain that organic material that is the basis of the food web, you need something to hold the leaves and twigs, to let those organic crumbs fall out. That's what woody structure does for a stream. We need to slow down the water, so we can retain that organic material."

Of course, if a stream has nothing but slack water, then it has no spawning and feeding habitat. "So you need it all," Christensen said. "About the best you can do is create as diverse a flow as possible, and hope you've hit on the right formula."

This summer, once the fry have emerged and had a chance to grow a bit, Christensen and company will put more wood in Belmont Creek's waters, hoping to add to their success. They'll do the same in Chamberlain Creek, further upstream on the Blackfoot.

Already, the ground water in Belmont Creek's big meadow is rising, McKenzie said. Soon, the creek will rediscover the meadow and its inclination to meander. And fisheries biologists won't have to hire draft horses to drag wood into the water.

"Even as large as they are, these pieces of wood are temporary," Christensen said. "They'll decay, they'll be covered with gravel, or they'll move downstream. But they'll have done their job. They'll have rebuilt the channel so natural forces can take over."

Almost like magic.

Reporter Sherry Devlin can be reached at 523-5268 or by e-mail at sdevlin@missoulian.com

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