FLOOD CONTROL FOR THE SACRAMENTO VALLEY ALONG THE AMERICAN RIVER

It is irrefutable that the Sacramento Valley needs greater flood protection as demonstrated by the devastating floods of 1986, 1995 and 1997.

Flood Control for Sacramento County Along the American River

The disturbing feature of the events was that each exposed a different weakness in our flood control defenses. The 1986 flood attacked the American River watershed and exposed the weakness of the Folsom Dam capability, and the levee system of the lower American and Sacramento Rivers, which were nearly broached. The 1985 flood attacked the local drainage system, flooding creeks, streams and canals, and demonstrated our surface drainage system was inadequate and in severe disrepair. The 1997 storm mercifully flanked the American River watershed, but destroyed levees north and south of the County, inundating the flood plains. Yet, none of these storms exceeded a 100-year flood.

The History - The Valley flood control concept, through 1930, was that floods could be controlled through levees. In 1930, when the state planned, federally built and managed Central Valley Project began, dams, canals and water interchange systems altered the frame of reference for flood control. The construction of Shasta, Folsom and Oroville Dams added to the flood protection, and provided means for controlling flood flows in their rivers. The 1986 flood convinced most people of the wisdom of building dams in the watershed. During that flood American River levees, designed to hold a water flow of 115,00 cubic feet per second (cfs), barely held as the Folsom Dam released an unprecedented 130,000 cfs. At the City of Sacramento, during the floods highest point, 650,000 cfs passed down the Valley, 50,000 cfs above the flow the levees were designed to contain. Had it not been for the dams holding back peak flows, the total Valley peak outflow would have exceeded a million cfs, which could have inundated the City OF Sacramento..

After the flood of 1986, the State of California and the Sacramento Area Flood Control Agency (SAFCA) both selected the 200-year flood event as the minimum requirement for the Sacramento Valley, which was intended to provide guidance when the mix of options was selected to achieve the required protection.

In 1989 the US Army Corps of Engineers (COE), in cooperation with the State of California Reclamation Board and the Department of Water Resources, published an Information Paper on Alternatives for flood control of the American River Watershed. A major finding was that "the only way to achieve a 200-year or greater level of protection along the mainstream of the American River is with a new flood control storage space at or near the Auburn Dam site." Included were improvement of levees, and the banks of the Natomas East Main Drainage Canal and Cross Canal, to protect Natomas and reduce flooding along lower Dry Creek.

In 1990, SAFCA published a Staff Report titled, "American River Watershed Investigation Project Consensus." It recommended SAFCA adopt a Resolution to the State and the COE that the COE develop a flood control protection project consisting of an expandable flood control dam near Auburn; raised levees in and around the Natomas Area; and re-operation of Folsom Reservoir to provide additional flood water capacity until the Auburn Dam was completed.

In 1991, the COE published a Feasibility Report which described three types of dams as options, i.e., dry dams, a flood control dam that could be expanded to provide water and power, and a full service dam that provided flood control, water, power, and upgraded recreation facilities from the outset. There were two sizes of flood control only dry dams, i.e., a 200-year and a 400-year dam. The COE recommended the 400-year dam. SAFCA selected the 200-year expandable dam.

This recommendation, endorsed by all local elected officials, was carried to Congress in 1992. Despite the unanimity of our local leaders and Congressmen, Congressman George Miller, then Chairman of the Natural Resources Committee, derailed the project. He wanted a non-expandable dry dam, backed by a quasi-National Recreation Area, which would have ended any possibility to expand the dam for water and power. Congressman John Doolittle objected, insisting the dam be truly expandable. There was no resolution, and it was dropped from the Public Works Authorization. However, money was provided for the COE to examine other alternatives for flood control.

In accordance with the instruction, the COE prepared a Supplemental Alternative Report (Nov. 1994) to the Feasibility Report. Based on the 1991 Report and the Supplement, the COE narrowed options to three: They were:

The Folsom Modification Plan which lowers the winter water level by 720,000 acre feet; lowers the dam's spillway; enlarges the river outlets; shores up the levees of the lower American River and heightens levees on the east side of the Sacramento River. The level of protection is the 180-year storm. Cost, about $326 million

The Folsom Stepped Release Plan which lowers the winter storm level of the Folsom reservoir by 670,000 acre feet; lowers the spillway, and enlarges the river outlets. It increases the maximum release of water from Folsom Dam from 115,000 cfs to 180,000 cfs, which necessitates extensive modification of downstream levees and weir bypasses; and include modification to Yolo levees to handle the increased flow. Level of protection is the 235-year storm. Cost - $528 million.

The Detention Dam Plan, a 500-year dam, somewhat equivalent to the 400-year dry dam of the 1991 proposal, with some modifications. These include control gates in the river outlets, operating Folsom Dam with the traditional 400,000 acre feet of flood control space used before the 1986 flood and retaining Folsom's maximum release at 115,000 cfs, deleting need to modify Folsom Dam. Cost - 934 million.

In 1996 SAFCA, along with local politicians, agreed to support the COE Folsom Stepped Release plan alternative. During the 1997 January flood, the Bureau of Reclamation, having implemented a Folsom re-operation recommendation to lower the water level of the reservoir by about 600,000 acre feet in the winter, was able to handle American River flows without serious damage to the river's parkway, or the City levees. However, massive levee failures north and south of the County resulted in killing nine people and forcing more than 100,000 people to abandon their homes.

In March 1998 SAFCA and local politicians voted to support the Folsom Stepped Release Plan for changes to Folsom Dam and raising the height of the American River levees to handle 180,000 cfs water releases during potential flooding events. This severed the coalition of local Congressmen supporting a flood control dam at Auburn. It pitted Congressman Matsui and SAFCA, as supporters of the Stepped Release Plan, against Congressman Doolittle who fostered a plan to rebuild the coffer dam at Auburn. The coffer dam, providing about the same level of flood protection as the raised levees, would trap flood water flowing down the north and middle forks of the American River at the Auburn site rather then permitting the flow to hit the Valley. Both plans agreed with changes recommended for the Folsom Dam. Although the Senate agreed with the levee raising plan during Washington D.C debates, the stand-off between Congressmen Matsui and Doolittle stymied any final resolution.

In 1999 the Senate re-introduced the levee raising plan. However, in the House of Representatives both the plan to raise the levees, or to rebuild the coffer dam, were dropped and replaced by a suggestion that Folsom Dam be raised, along with other changes to increase its flood control capability.

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