Battling Raging Waters

Just after Christmas, DWR meteorologist Bill Mork saw trouble brewing on the horizon—a series of storms that could bring floods to rival those of 1955 and 1964. DWR staff immediately began preparing for the coming deluge. On December 29, the Flood Operations Center staff went on round-the-clock shifts as the Sacramento River rose to the 25-foot warning stage.

Lake Oroville stood ready with approximately 850,000 acre-feet of flood reservation space. Daily levee patrols were initiated, focusing on levees in the Delta and along the Sacramento and San Joaquin rivers. Flood managers awaited the heightened activities that would require long hours to determine how best to prevent and deal with flooding along those systems.

When the storms struck, they unleashed torrential rainstorms along the upper Feather River and Shasta watersheds. A total of 25 inches fell in the Feather River basin over an eight-day period ending on Jan. 3. Peak rainfall totals for that period at Bucks Lake in the Feather River watershed exceeded 42 inches.

The storms produced tremendous runoff. Inflows to Lake Oroville stayed at record levels for more than 16 hours and peaked at over 300,000 cubic feet per second on New Year's Day. Oroville and other major Northern California reservoirs, such as Shasta, were barely able to contain the torrents within downstream river channels. Two levee failures occurred in the upper Sacramento flood control system. A Feather River levee broke on Jan. 2, inundating Arboga and part of Olivehurst in Yuba County. Two days later, a levee break along the Sutter Bypass flooded more than 40,000 acres in Sutter County and threatened the town of Meridian.

Flows out the Sacramento River flood system—via the Sacramento River and the Yolo Bypass—exceeded 600,000 cfs. (The record is an estimated 650,000 cfs in February 1986.) In the Sacramento metropolitan area, the Sacramento River crested at 30.4 feet at the I Street Bridge, just under the 1986 record of 30.68. Although Folsom Lake was able to contain outflows within the American River's 115,000 cfs channel capacity, only a few more inches of rain on the watershed would have stressed that system to the limit —and resulted in a record stage at I Street. While outflows from Folsom and other major reservoirs were quite large, they were only one-third to one-half of peak inflows.

Cumulative flows through the San Joaquin system made it the biggest flood of record in modern times. (Because flooding in the system is typically caused by snowmelt, the channel capacities are much smaller than in smaller than i n the Sacramento River system.) Contributing to that region's flooding were record high inflows to New Don Pedro, necessitating releases into the Tuolumne River several times larger than the design channel capacity through Modesto. Levee breaks caused flooding from the mouth of the Tuolumne River at its junction with the San Joaquin River north to Paradise Cut, about 10 miles south of Stockton. Heavy inflows also caused Friant Dam to overtop its spillway, releasing very high flows and causing a series of levee breaks downstream from Highway 99.

The San Joaquin River Flood Control System was overwhelmed. All but one of the reclamation districts on the lower San Joaquin River, from the Tuolumne River to Manteca (Mossdale Bridge), were inundated by floodwater after levees broke from the excess flows. In all, nearly two dozen levee breaks occurred along the San Joaquin system.

In the Delta, three islands— Dead Horse Island, McCormack-Williamson Tract, and Stewart Tract, as well as Prospect and part of Pescadero and Reclamation District 2095 —were inundated. Despite windy conditions and the highest tides of the year, tough flood fights by hundreds of workers—personnel from DWR, California Conservation Corps, and California Department of Forestry along with Department of Conservation inmates—preserved the rest of the 60 Delta islands.

The Cosumnes River, largely uncontrolled by upstream storage, experienced the highest peak flow in 90 years of record. These flows broke through private levees and caused considerable damage to vineyards and rural homes. Eventually these floodwaters closed Highways 16 and 99 and Interstate 5.

In other battles against the raging muddy waters of the Sacramento, Feather, Yuba, and San Joaquin river systems. Local reclamation districts worked around the clock for weeks to strengthen levees, sandbag boils, and build emergency berms. Their efforts were aided by local public safety organizations and inmate crews from the Department of Corrections.

Meanwhile, Flood Operations Center staff, assisted by individuals from throughout the Department, made warning calls to agencies and communities along threatened waterways, answered inquiries from the public, briefed the media on the latest news, and coordinated flood fight efforts throughout Northern and Central California.

As this issue of DWR News goes to press, the historic New Year's flooding has stimulated tremendous public interest on the issues of flood control, levee safety, reservoir operations, and development within floodplains. The Governor called a special session of the Legislation to deal with flood issues. Legislators also held a series of informational briefings on the floods to gather information for possible legislative action on flood protection issues.

On Jan. 10, Governor Wilson issued an executive order directing his Water Policy Council to create a Flood Emergency Action Team. Resources Secretary Douglas Wheeler chairs the team which includes DWR Director David N. Kennedy. After consulting with local citizen advisory groups, local officials and federal agencies, the Flood Emergency Action Team will report on several key flood-related issues, including a plan for long-term repair and general maintenance of Central Valley flood control facilities. A preliminary report was released in early February, with a final report due in May (see sidebar on "Feat Recommendations").

Near the end of January, Bill Mork saw a second storm system approaching. Though not as intense as the first, more rain meant more flooding with the ground saturated, levees stressed, and the waterways running high. Luckily, the system moved through faster than expected, leaving certain areas with less precipitation than estimated. But areas in Sacramento and Placer counties—such as Rio Linda, Arden Arcade, and Granite Bay—did not escape flood flows from local streams and creeks.

The lower San Joaquin River crested for the second time, setting a new record at Newman but less than the early January levels downstream at Vernalis and Mossdale, where multiple levee breaks reduced the river stag e. The entire San Joaquin system remained at or above capacity into late February.

As of this article's writing, levee repairs continue along the Feather and San Joaquin rivers. The Flood Operations Center remained on 24-hour alert until early February, but will keep up their virgil until the end of the rainy season.

(Footnote: Even before this year's flooding began, work was completed on two important flood control projects in the Sacramento area and planning started on a project to protect the city of West Sacramento. See "The Continuing Quest" in this issue.)

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FEAT Recommendations

Among key recommendations included in the Feb. 10 Preliminary Report of the Governor's Flood Emergency Action Team are:

• Direct DWR to install new stream gauging stations and telemetry in areas found deficient during the floods;

• Direct DWR to establish a new Levee Rehabilitation Unit to work with the U.S. Army Corps of Engineers to restore levees to pre-flood conditions, prior to the 1998 flood season;

• Direct DWR and the Governor's Office of Emergency Services, working with affected counties and landowners, to support development of local plans for emergency repair of "private" levees and submit those plans to Federal Emergency Management Agency for federal funding;

• Direct OES to conduct workshops, with State, local and federal agencies, and the media, in areas at risk during this flood season, to review roles and procedures related to dissemination of flood information and public warnings; and

• Direct CALFED, as part of their planning, to optimize use of Proposition 204 and Central Valley Project Improvement Act funds for projects which incorporate both flood control and habitat restoration.

Other recommendations covered the reimbursement of federal disaster claims, State assistance for national parks damaged by the January floods, a campaign to promote tourism in flood-damaged regions, and a number of requests for federal action on levee repairs and rehabilitation.
Governor Wilson had already directed OES to advance $8 million in State funds to counties most affected by the flooding and DWR to pump out ponded water on 70,000 acres of land, which was posing a threat to existing levees and causing a health and safety hazard.

A second report, the 120-day report, will take a comprehensive look at the State's longterm flood protection needs and review the overlapping responsibilities of private, local, State, and federal authorities in maintaining and improving the State's levee system and its offsite storage system .