Associated Press

A 'bulkhead gate assembly' for the new Folsom Dam auxiliary spillway under construction in Vancouver, Wash. (U.S. Army Corps of Engineers) — A bulkhead gate assembly for the new Folsom Dam auxiliary spillway under construction in Vancouver, Wash. (U.S. Army Corps of Engineers)

FOLSOM, Sacramento County — A 600-mile stretch of highway, including a long section of Interstate 5 in California and Oregon, will be shut down in sections to make way for new floodgates being shipped to Folsom Dam, the Sacramento Bee reports.

The new gates are part of a $900 million auxiliary spillway project designed to release water earlier and faster during a flood, providing greater protection to the Sacramento region from floods on the American River. (Ironically, Folsom Lake, the reservoir behind the dam, has been near historic lows due to the current drought. However, runoff from the Sierra Nevada through the American River watershed has the capacity to rapidly fill the lake and require massive releases downstream.)

Each assembled gate is about the size of 12 school buses strapped together in a cube. Though they are being transported in pieces, Interstate 5 from just outside Portland, Ore., and other highways will have to be shut down to accommodate them. The first shipment is expected later this month.

"It'll be pretty interesting, pretty spectacular, for them to be moving something this large down from Oregon," said Rick Johnson, executive director of the Sacramento Area Flood Control Agency. "I anticipate it'll be similar logistics to moving the space shuttle."

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Interstate 5 will be closed only at night, with the trucks delivering the different pieces staying off the roadway during the day, said Army Corps project manager Katie Huff. The contractors on the project are working with the California Highway Patrol, state transportation department and local governments on the details of the deliveries, which will take months to complete, according to the Bee.

All the parts are expected to be on site by May.

Folsom Dam's refurbishment is largely being funded by the federal government. It is expected to be completed in 2017.

Here's a U.S. Army Corps of Engineers video describing fabrication of the big spillway gates:

Folsom DamFolsom Dam

Moving New Floodgates to Folsom Dam Will Require I-5 Closures