Officials inspect a gaping 300-foot hole in the concrete spillway at the Oroville Dam in California. Water levels behind the dam are rising, leading to a potentially unprecedented emergency runoff. Photo courtesy Kelly Grow/California Department of Water Resources
Feb. 10 (UPI) -- Officials in California prepared to implement a never-used emergency plan to release millions of cubic feet of water building up behind the Oroville Dam after a gaping hole formed in its spillway.
Bill Croyle, deputy director of the California Department of Water Resources, said the dam itself remains in no danger of breaching, however due to unprecedented amounts of storm water flowing into the reservoir after torrential rain in the region, the water level is now 14 feet away from rising over the dam.
If the water continues to rise and the compromised concrete spillway, which was found Thursday to have a gaping 300-foot hole, can't handle the runoff, an unimproved emergency spillway would be used, something never attempted in the dam's nearly 50-year history.
Such a move could have untold ecological consequences for the Feather River below, which is home to the state's largest salmon hatchery.
Dam officials reopened the floodgates into the damaged spillway, setting off a torrential waterfall, but even that wasn't enough to stem the rising tide behind the dam. The tremendous waterfall headed down the compromised spillway and an adjacent hillside was letting out 35,000 cubic feet of water per second, but that paled in comparison to the 190,000 cubic feet per second of storm water flowing into the reservoir, the San Francisco Chronicle reported.
At 770 feet high, Oroville Dam about 75 miles north of Sacramento is the nation's tallest. Its reservoir diverts fresh water to much of Central California's farmlands and homes, and businesses in Southern California.
Department of Water Resources employees were rushing Friday to clear the unpaved emergency spillway of brush and debris in the event it is needed, with the hope of limiting damage to the delicate fish hatcheries below the dam. At the same time, wildlife experts were rushing to save as many as possible of the millions of juvenile salmon too young to be released into the wild and millions more eggs waiting to hatch. Salmon eggs require clear, cool shallow water to hatch and the muddy torrent already plunging down the main spillway into the Feather River was enough to cause many of the eggs in the hatchery to be lost, officials said. A failsafe filtration system meant to protect the eggs was quickly overwhelmed, allowing murky, mud-filled water to blanket the hatchery.
Those fish that could be saved were loaded into tankers and moved several miles downriver, where ecologists said the effects of the muddy water would be less harmful, allowing the young fish to survive.
In addition to the ecological impact of the swelling water, there is a long-term effect on the fishing industry up and down the Pacific coast. Most of the mature salmon caught in the open ocean water for human consumption are grown in the Feather River, creating a potentially devastating loss to fishermen in California and Oregon.
