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State may reduce water releases at troubled Northern California dam, even as new storm looms

State officials say they may slow down the spigot at the troubled Oroville Dam, even as they face approaching storms.

"This next storm won't pose a risk to the emergency spillway or the work we're doing," William Croyle, acting director of the California Department of Water Resources said at a noon press briefing in Oroville, California.

He explained that the planned ramp-down of water releases from the primary spillway is a result of both progress in lowering the dam levels and also as a precautionary move because "we don't want to tear our flood-control structure up any more than it has."

Construction crews continued to make repairs on the eroded emergency spillway Wednesday afternoon in an around-the-clock operation that Croyle said won't stop unless ground and wind conditions don't allow for it. They were using helicopters, heavy machinery and dumping rocks into the crevice of the damaged emergency spillway.

"I can't believe how much work...they've done in the last couple of days to move material into the area below the emergency spillway," said Croyle, whose agency operates the dam.

As of noon, he said there were 96 crew onsite working on repairs, but that is down from the 125 number provided in the morning by officials.

Despite plugging the gouged hole in the emergency spillway with rocks, Croyle said challenges remain for California's second-largest dam.

"We are still working through a very difficult situation at the dam," he said. But he reiterated that the "dam structure is safe."

Late Tuesday, President Donald Trump approved federal emergency aid for California as a result of the potential failure of Oroville Dam's emergency spillway, and separately to help recovery efforts in areas affected by January storms. Oroville Dam is the nation's tallest earthen dam.

Also, residents started returning to their homes Tuesday after the mandatory evacuation order was lifted although some emergency shelters still had evacuees as of Wednesday morning.

Businesses also started reopening in the affected areas but there was concern the financial impact of the mandatory evacuation may stick around for some time.

"Normality seems to be taking hold," Sandy Linville, president and CEO the Oroville Area Chamber of Commerce said Wednesday morning. "People are really spent from the stresses of the last few days. Not only are you looking at businesses being hurt, but you're looking at the trickle-down effect to the individual person being hurt financially from not working."

According to Linville, there still remained a "heightened awareness" of the Oroville Dam situation with the new storm approaching. "There are still about 300 people who choose not to come back and still are at the evacuation center in Chico."

Indeed, after lifting the mandatory evacuation order Butte County Sheriff Kory Honea said Tuesday that "an evacuation warning" would remain in effect given the possibility of future changes in the situation.

Speaking to reporters Wednesday, the sheriff said preparation still is important for residents in the downstream communities. "This is an opportunity for them to get things together…if the risk level increases and there's a need for us to issue an evacuation order," he said.

The approval of the emergency declaration late Tuesday will provide money for the area and authorizes the use of federal equipment and resources to alleviate the impact of the dam incident. That allows the state to potentially get up to 75 percent federal reimbursement for "required emergency protective measures," which a Federal Emergency Management Agency spokesperson said includes things such as cots, water, blankets and food for sheltering evacuees but not the cost of repairing the dam's troubled emergency spillway.

The FEMA spokesperson said the California governor would need to put in another request to the president to cover cost-sharing on spillway repairs.

Separately, the major disaster declaration was made for the deadly January storms that caused flooding and mudslides. It also will allow FEMA to provide funds to help with debris removal as well as repair work to bridges, roads and other public facilities.

"I want to thank FEMA for moving quickly to approve our requests," Gov. Jerry Brown said in a statement. "This federal aid will get money and resources where it's needed most."

A series of new storms is expected to approach Northern California and the Oroville area as early as Wednesday night. The mountains above Oroville are forecast to get 2 to 4 inches of precipitation by the end of Thursday, and snow levels will be lower than last week's storm so that will mean more snow and less rain and runoff into the lake, according to the National Weather Service.

Lake Oroville Dam, located in the western foothills of the Sierra Nevada mountains, gets major inflows from the Sierras and will be tested again in the spring when the snowpack begins to melt. The state's snowpack in the central Sierras region where Oroville is located sits at 183 percent of normal.

Heavy equipment moving rocks for use in an attempt to repair damaged spillway at Lake Oroville Dam in Oroville, Calif., on Feb. 13, 2017.
Brian van der Brug | Los Angeles Times | Getty Images
Heavy equipment moving rocks for use in an attempt to repair damaged spillway at Lake Oroville Dam in Oroville, Calif., on Feb. 13, 2017.

Cal Fire Capt. Dan Olson, a spokesman for the Oroville incident, said Wednesday that things were starting to "return to normal" for residents in the city of Oroville, one of the communities evacuated Sunday when the hole in the emergency spillway posed an immediate risk of a large, uncontrolled flow of water down the Feather River.

Overall, nearly 200,000 people were evacuated downstream in three different counties.

The evacuation Sunday occurred after state and local officials grew concerned the hole near the top of the emergency spillway could cause a 30-foot wall of water down to the Feather River and tributaries.

The unlined emergency spillway — essentially a hillside — experienced significant erosion after the reservoir overflowed Saturday, at one point reaching an elevation capacity of 901 feet. That was the first time the emergency spillway was used in the dam's 48-year history.

Even so, engineers have been using the damaged primary spillway this week for significant outflows to lower the lake level as new storms approach. Officials that the primary spillway appears to be holding up despite its own erosion problems but reducing the outflows was still seen as a prudent measure.

As of Wednesday at 2 p.m. local time, the reservoir level was 876 feet and continuing to decline as a result of outflows from the primary spillway. Engineers want to lower the level to 850 feet as a flood-control buffer. The primary channel was found to be damaged too last week after significant water releases from major winter storms.


(UPDATED: This story was updated with details from Wednesday afternoon's press conference and to specify what costs are covered by the federal government's emergency declaration.)