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Plugging Away at River Restoration
The long-abandoned floodplain meadows that once acted like giant sponges on the upper Feather River—absorbing heavy flows and releasing them throughout the year—are beginning to do so once again, thanks to an experimental restoration technique called "pond and plug." In 1995, a public-private partnership known as the Feather River Coordinated Resource Management group began experimenting with the technique on several tributaries. After monitoring these projects for several years, the group is so encouraged it plans to pond and plug many more miles of damaged mountaintop meadows.
Once lush with tall grasses and wildflowers and alive with bugs, birds, beaver and deer, many of these vast alluvial meadows, nestled among steep Sierran slopes, have become deserts. A panoply of activities—among them, ranching, railroading, and mining—dating back to the 1860s resulted in the dewatering of the meadows as the streams that meandered through them were moved to make room for trains and cows. After the channels were relocated and began to erode and downcut, the meadows turned dry and unproductive, no longer acting as sinks for the sediment, water and nutrients delivered from the uplands in winter runoff, explains Jim Wilcox, Restoration Project Manager for the 22-member partnership Before large-scale manipulation of the landscape took place, the meadows buffered the effects of flood and drought, says Wilcox, storing floodwater as groundwater and releasing it gradually into the streams over the course of the year. Now, however, during big storms, high flows race through the relocated, deep, narrow gullies like a flume, says Wilcox. Not only does the fast-moving water exacerbate downstream flooding, but the streams continue to erode and downcut, some by as much as 15 feet, to soils deposited 7,000 years ago.
To restore the meadows and their flood storage capacity—and to heal the erosion and gullying—the group is using the pond-and-plug method first used on Maggie Creek in Nevada by river expert Dave Rosgen. Pond and plug involves first moving the stream back to its historic location—sometimes hundreds of thousands of feet across the meadow.
"You can usually find at least pieces of the old stream if not the whole thing," says Wilcox. After workers return the stream to its original location, they dig deep ponds next to the old gully and use the excavation spoils to plug the gully so that it no longer drains the meadow. The ponds create habitat for waterfowl and other critters as the groundwater rises to fill them. Tenacious willows that have survived along the gullies are transplanted along the new (original) stream channel, while the native meadow sedges, grasses and wildflowers quickly return on their own, helped by the dormant seed bank and fungi in the excavated soil. The invasive star thistle and sagebrush that have taken over begin to retreat.
How successful has pond-and-plug proved on the Feather River?
Wilcox has been monitoring the group’s first project, the restoration of Big Flat Meadow/Cottonwood Creek in the Plumas National Forest (and the first pond-and-plug project in California) since 1995. There, the creek had been captured by an irrigation ditch and had responded by incising 14 feet in places. After the Feather River folks ponded-and-plugged the old gully and recreated the original stream channel, the meadow began to come back to life, with flood flows spreading across and infiltrating its plain. A modified grazing regime has allowed the restored creek to grow thick with willow once again.
"The birds are back, the waterfowl are back, even the fish are coming back," says Wilcox.
Downstream users benefit too. "In January and February, when the Pineapple Express comes in," says Wilcox, referring to heavy rains from Hawaii, "Lake Oroville has to dump water." But with the meadows performing their old function of sponge, some of the runoff is released later in the year, in May or June, making what’s coming out more usable downstream.
With over 50 projects (10 of them pond-and-plug) and studies under its belt, the Feather River partnership is well on its way to restoring the entire upper watershed, a land area about the size of Rhode Island. Next, Last Chance Creek will get a second chance, with a $980,000 grant from CALFED; construction on the site is already underway.
An ongoing challenge will be reintegrating cattle into the landscape. To that end, landowners—whether private or public—are required to sign an agreement to maintain, monitor and manage the restored landscape.
"These areas won’t support the thousands of head you would have found in 1900," says Wilcox. "But some grazing may be possible with reduced numbers and by changing the season of use." Should problems arise, Wilcox and the rest of the partnership will be there to work them out.
"Because we’re place-based, we’re with our projects forever," says Wilcox.
Contacts: Jim Wilcox or Leslie Mink (530) 283-3739 LOV
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