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

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

"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.

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.

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."

"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.

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

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.