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MEDIA CENTER - Press Set aside land along rivers to prevent flood
disasters About once or twice every decade, California receives abundant rain and snow, which then runs off the Sierra into Central Valley rivers and streams, where high flows threaten lives and property. This spring exemplifies this type of wet year. Snowpack is about 180 percent of average in the Sierra, the reservoirs are brimming and the rivers are flowing deep and fast. All of this has raised serious concerns about the stability of our state's levees. Much has been said in Sacramento about a disaster in the making in the Sacramento-San Joaquin Delta. But the flood risk is found along all of the state's rivers, wherever people have decided to build on flood plains. One solution proposed by flood managers to avert a disaster is to build new levees and strengthen existing ones. While levees certainly can and do protect lives and property, they do not represent a silver bullet. As observed over the years by the state's flood-plain experts, there are two kinds of levees: those that have failed and those that will. When they do fail, the flooding is even more devastating. A case in point: In June 2004, a levee on the Jones Tract near Stockton broke, flooding more than 12,000 acres of farmland. Another similar disaster in the delta could interrupt the state's water supply system for months, causing a major disruption to the state's economy of New Orleans proportions or larger. In the Sacramento area, explosive development in the Natomas Basin, a low flood plain, will place more than 20,000 homes at risk of being flooded. Flood experts had estimated that levees would protect against a '100-year' flood, but the protection afforded by those levees was downgraded after an updated analysis found several areas where the levees have been eroded to a critical point. The good news is there are other tools in the flood-control toolbox that we can, and should, use. One is expansion of river floodways to allow rivers to do what they naturally do: flood. By removing homes and other buildings, and even excluding agriculture, from flood-prone areas, floodwaters are given a place to go without harming lives and property. This also has the advantage of taking pressure off levees in other areas by providing 'transitory floodwater storage.' In Stanislaus County on the Tuolumne and San Joaquin rivers, several projects achieve just that. After the 1997 floods, the USDA-Natural Resources Conservation Service purchased permanent flood-plain easements from landowners who had suffered repeated flooding. With help from the California Department of Water Resources and other agencies, the NRCS was able to expand the floodway, permanently preventing flood damage from occurring on these properties ever again. One of these, the Big Bend Restoration Project, was
undertaken in partnership with the Tuolumne River Trust, has been a
tremendous success. As the Tuolumne River began rising in March, we
saw our labors bearing fruit as floodwaters began inundating the recently
purchased land in a nondamaging way. This reduced pressure in other
locations along the Tuolumne. |
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