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Clear Creek Comeback
An ambitious restoration plan that uses one problem to fix another is underway on 2.5 miles of Clear Creek, the first major tributary to the Sacramento River downstream of Shasta Dam.
Clear Creek’s problems began in the 1840s, when it was mined for gold — first by hand, then hydraulically, then with dredges. Later, the creek bed was harvested for its gravel, which destroyed spawning opportunities for fish. Large pits for excavating gold and gravel also wreaked havoc on the floodplain; huge piles of tailings still clutter the landscape. "Basically, the floodplain was mined out almost valley wall to valley wall," explains Scott McBain, one of the fluvial geomorphologists designing the restoration project for the Lower Clear Creek Restoration Team, a group of environmentalists, private landowners and multi-agency stakeholders.
Dams — large and small — added to the creek’s troubles. In 1903, Saeltzer Dam was built across the stream’s lower reaches to provide water for agriculture and other users. Then in 1963, Whiskeytown Dam was plopped in nine miles upstream, further depleting the stream of spawning gravels and flows. As a result, the creek bed dropped about seven feet, down to the clay hardpan. Not only could fish not find good spawning and rearing habitat, but adults and juveniles were being trapped in the pits in the floodplain when low flows cut off their access to the main channel. As a result of all of these activities, the channel itself became highly braided and unstable. "One of the major goals of our project is to restore a dynamic alluvial channel within the limits of the regulated flow regime," says McBain. "We want to rehabilitate the form and function of the channel and floodplain, reverse the incision, decrease salmon strandings, and help the riparian vegetation come back on its own—we want to help the channel heal itself." If the restored channel begins to move back and forth across its floodplain on its own (similar to historical conditions), says McBain, that will be a sign of success.
Because of its large scale, the project is being implemented in phases. Phase 1 was completed in 1998 when 30,000 cubic yards of tailings were used to isolate several pits that were particularly problematic for fish, says Jeff Souza with the Western Shasta Resource Conservation District. Phase 2 —partially completed — concentrates on filling pits in the floodway to change a braided channel back to a more functional, mostly single-thread channel, and recreating and revegetating the new floodplain. Phase 3 will use more dredge spoils to raise the incised bed of the stream off the clay hard pan and replenish gravels for fish. The last phase (scheduled for completion in 2006) will fill an old mining bypass channel and recreate the natural path of the creek.
The project is among the first of its kind, both because of its large scale and several design innovations. As part of Phase 2, old abandoned channels and depressions were designed as part of the floodplain, instead of a "laser-leveled" monotypic floodplain, says McBain. Backwater sloughs offer fish places to hide, yet their slopes are just steep enough to allow water—and fish—to meander back into the main channel. The floodplains are being planted with a variety of riparian species, including cottonwood, several species of willow, mulefat and others. Adjacent uplands will be planted with mulefat, valley oak, elderberry and other species.
The genesis of the project was several years ago when the Western Shasta RCD did a watershed analysis. The increase in flows that began in 1995 — the result of an MOU between the Cal Fish & Game, U.S. Fish & Wildlife and BurRec—led to an immediate increase in numbers of fall-run salmon, Souza says, so the Restoration Team’s predecessor decided that better flows—and better sediment transport and deposition for fish—were a high priority. Last summer, Saeltzer Dam was removed, which will allow fish better access to upstream habitat and improve gravel transport from upstream.
The total project is estimated to cost approximately $10 million. So far, CALFED has chipped in a healthy $3.5 million, and other agencies more than $1 million more. The Bureau of Land Management owns most of the land surrounding the channel and floodplain, so private property issues were minimal. The project is not without snags, however. Offsite wetlands must be created to compensate for filling of the mining pits, which were providing seasonal wetlands used by birds and other wildlife. And more recently, the potential of mercury in the dredger tailings used to fill the mining pits has become an issue. Mercury is a concern in the Clear Creek watershed because it was used in the gold-mining process to line the sluices on dredge barges—and a lot of it ended up in the creek’s waters and sediments. Although Clear Creek is not listed as an impaired waterway, the Regional Board has suggested that sampling and studies be done to make sure the restoration project is not inadvertently creating a larger problem, according to the Central Valley Board’s Guy Chetelat. "We’re just starting to learn about this issue and address it," says Chetelat. To that end, says Souza, the CALFED Science Board is helping the Restoration Team design a study to find out what’s there, how much mercury methylation (a chemical process that converts inert mercury to a more toxic form) is going on, and how significant any lurking "pockets" of mercury may be.
As it monitors the work it’s done so far, the team continues to plan the rest of this large-scale project. "As development continues, more pressure continues to be put on our resources," says McBain. "We need to do restoration on a similar or greater scale than the development of our watersheds. This is one of the first projects that does this. We’re breaking new ground here."
Contacts: Jeff Souza (530) 224-3250; Scott McBain (707) 826-7794x11; Guy Chetelat (530) 224-4997
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