 |
|
 |
| ||
|
Eco-Friendly Flood Control
What do riprap, coconut skins and creeping wildrye have in common? They're part of a plan Save the American River's Frank Cirill calls the river's "first real chance for meaningful restoration in 50 years."
The plan is the lesser known half of an October recommendation made by the Sacramento Area Flood Control Agency (SAFCA) to Congress and the Army Corps which includes multiple measures for protecting area cities and farms from floods. Most of the attention has riveted on the upstream Auburn Dam part of the plan - an environmentally unfriendly project with a $934 million pricetag many doubt the government can ever afford. The downstream levee and riverbank improvement half of the plan, however, has both solid funding and the hearty endorsement of environmental interests such as Cirill, Cal Fish & Game and U.S. Fish & Wildlife. This endorsement is attributed largely to the trust built up between natural resource protection and flood control interests over 22 months of participation in the consensus-building Lower American River Task Force, whose recommendations concerning the lower 26 miles of the river have been largely adopted by SAFCA.
"Flood protection used to mean lining the river bank with rock and letting nature take its course," says Scott McCreary of CONCUR, which facilitated the task force. "But this cooperative planning process has enabled engineers to sit down with biologists and develop a more careful, biotechnical approach."
This biotechnical approach - aimed at preventing erosion on at least four known critical reaches of the lower 13 miles of the river by 1999 - is a repair and restoration combo which begins with adding a rocky armor to the banks. Coconut fabric pillows or blankets are then placed over these fortifications, and filled or underlaid with soil and plant seedlings. The fabric keeps the soil in place until plants can become established.
Washburn says getting plants to grow in the "harsh environs" of the river is a huge challenge, as most of the time in such human-controlled river conditions it's either too wet, too dry or too hot to be very hospitable. Enter - creeping wildrye. This rye, as well as a sedge that goes by the Latin label of Carex barbarae, are both rhizomatous grasses native to the American River plain and tolerant of both sun and shade. As resource ecologist Jeff Hart explains it, they have a very dense matrix of underground stems called rhizomes - "a whole army of plants to hold the soil for our restoration work in place."
The earth and vegetation overlays, designed by Inter-Fluve's Dale Miller, will provide on-site mitigation for habitat lost during the extensive bank stabilization work called for by the SAFCA plan. The plan also includes off-site mitigation - 160 acres of hayfield planted on a elevated river terrace. The river level has sunk so much over the years with drought and diversions that "in a sense, the river has lost its intimate relationship with the flood plain," says Hart. "We're trying to recreate that nexus."
Hart's design for this mitigation site in the Discovery Park/Woodlake area will excavate 160 acres back down to a more frequently floodable level, then grade and irrigate (with stormwater) to restore riparian and seasonal wetlands. The design breaks the site down into eight modules that can be developed incrementally over the years and function both independently or in concert. Washburn says the restoration of each module will be financed by a nearby local public or private works project in need of the excavated soil. Washburn says the site could also serve as a mitigation bank for the Sacramento region.
Such bank protection and restoration measures will help the region emerge from what has been a largely reactive and consequently environmentally destructive flood control mode, says Washburn. The 1986 flood, for example, led to emergency rip-rap dumps up and down the river.
"We've now institutionalized a collaborative, task force approach that will enable us to stay ahead of the game," he says. "We're doing restoration we'd never be able to fund unless we'd coordinated it with flood control," says Hart.
Contact: Tim Washburn (916)440-7606
[ ABAG HOME | SFEP HOME ]
Copyright © 2002, San Francisco Estuary Project