Clean & Complex by Mike Bader
This is part two in a three-part guest blog series on bull trout conservation efforts in Western Montana.
Biologists have summed up bull trout needs with the Four Cs: Cold, Clean, Complex and Connected. In last week’s blog, guest writer Mike Bader took us through the first “C” for cold, and explained how bull trout require colder water than other salmonids, with ideal maximum temperatures at 59 degrees or less.
This week, Mike is taking a look at the clean and complex factors—and how our waters in western Montana are stacking up.
A little background
Historically, the Clark Fork boasted high numbers of bull trout.
Historically, just about every mountain stream and river system in the northern Rockies west of the Divide had native bull trout. Yet the health of the Clark Fork Basin has been damaged by a century of resource exploitation. Populations of native bull trout and westslope cutthroat trout have been dramatically reduced, and are now often restricted to the very highest mountain streams. Many of the main bottom streams have been so altered and compromised, that they are now past their ability to support robust populations of native trout. Bull trout were listed as a threatened species via the federal Endangered Species Act in 1998.
In an effort to help prioritize bull trout recovery efforts, the U.S. Fish & Wildlife Service recently finalized a critical habitat designation for bull trout. Covering approximately 20,000 stream miles, 1,000 miles of coastal shoreline and over a half million acres of lakes and reservoirs in Idaho, Montana, Oregon, Washington and Nevada, it is one of the most sweeping agency actions of its kind.
The central purpose of critical habitat is to protect the Primary Constituent Elements of bull trout habitat, which are: low water temperature, low sediment levels, connectivity for migration, sensitive spawning grounds, and shaded riparian habitat.
Clean machines: Bull trout take their water pure
The South Fork of the Flathead meets the 4 "Cs"
So what does “clean” mean to a bull trout? Biologists have determined that, from the perspective of this native fish, it’s the high levels of fine sediment present in the streambed that are “dirtying” the water. Fine sediments can fill in the spaces between rocks and gravel in the streambed, smothering bull trout embryos and severely reducing the survival and emergence of new fry. To promote bull trout spawning success, the streambed should ideally be composed of 20% or less of these fine materials.
Unpaved roads—often old logging and mining roads—are a primary source of the fine sediment. Improperly installed culverts can also increase fine sediments in a stream, as can many stream crossings and clearcuts on steep slopes. All of these sources have the potential for catastrophic landslides and scouring during extreme weather events such as heavy rain on snow. Grazing in and around riparian areas can also increase fine sediment, and might also lead to trampled banks and further erosion.
It’s Complicated: The bull trout is a complex creature
To be “complex,” the habitat needs to have varied elements, such as overhanging vegetation, logs, or large rocks within the stream—all which provide deep pools and hiding cover for fish. Scientific studies show there has been a loss of “recruitment” of large woody debris within bull trout streams due to removal of streamside vegetation and forests. In a relatively undisturbed forest, trees fall into the streams, creating diversity and complexity. But when riparian forestland is cleared, this natural process is interrupted. Biologists suggest maintaining riparian buffer zones at least 150 feet wide on each side of a bull trout-bearing stream.
So how are our waters measuring up?
Newly restored floodplain at Milltown
How clean and complex is the Clark Fork habitat? Things are certainly looking up for the bull trout. A crucial element in the ongoing restoration effort of the basin was the removal of the Milltown Dam near the confluence of the upper Clark Fork and Blackfoot Rivers. This major dam blocked spawning migrations for native trout, and also held back a century of toxic mine tailings. In 2011, the massive dam removal and restoration project—headed by the U.S. Environmental Protection Agency and the State of Montana’s Natural Resource Damage Program—is nearing its end. The dam is gone, the natural flow of the river has been restored, a new floodplain has been established and re-vegetated, and much of the toxic tailings have been removed. Thus, the threat of catastrophic flushes of toxic sediments downstream has been dramatically reduced.
Now, as the Milltown project winds down, the restoration focus is shifting to the Upper Clark Fork between Warm Springs Creek and Flint Creek. The Superfund cleanup on the Upper Clark Fork mainstem will cover over 43 river miles between Butte and Missoula, and offers a tremendous opportunity for an integrated, complete restoration in the upper stretches of the Clark Fork. Conservation groups, agency representatives, public officials, and landowners are working to heal degraded and dewatered streams throughout the Upper Clark Fork valley– all while providing education and outreach to inspire new river stewards for the future and help protect irrigated agriculture as a thriving, viable way of life.
As a primary indicator of water quality and watershed health, bull trout recovery is important to the future of all wild trout. The current restoration effort is already enhancing economic opportunities, revitalizing our fisheries, improving our water quality, and connecting local citizens with good-paying restoration jobs. When conditions improve for the bull trout, benefits come to all species—even to ourselves.