California is asking the federal government to pay 75 percent of the hundreds of millions of dollars in repairs to the badly damaged spillways at the nation's tallest dam, a state water agency spokeswoman said Monday.

The question of whether taxpayers or the water contractors that get water via the Oroville Dam would foot the biggest share of the bill has been one of many contentious ones in the aftermath of this winter's damage at the dam, which is an anchor of the state's water supply system.

Heavy flows of water in and out of the half-century-old structure in February gouged massive holes in both of the dam's water-release spillways, forcing the evacuation of 188,000 people downstream for two days. The Department of Water Resources is rushing to strengthen the damaged main spillway before the next rainy season.

The state has begun applying to the Federal Emergency Management Agency to ask for federal funds to cover 75 percent of all construction work there, water department spokeswoman Erin Mellon said. President Donald Trump agreed to designate the dam crisis as a federal disaster earlier this year, making it eligible for federal financial assistance.

As far as state officials are concerned, the "construction work is all considered emergency work because of the public safety concerns," Mellon said.

State water contractors who get water via the dam's Lake Oroville, the state's second-largest reservoir, would pay for whatever remaining costs that "FEMA and other sources like FEMA" don't, Mellon said.

FEMA has not yet told California whether it agrees that all of the repairs planned at the Oroville Dam site are an emergency that qualifies for the federal disaster funding

Last week, the Department of Water Resources obtained a $500 million letter of credit to finance the repairs ahead of any reimbursement.

Repair costs so far come to about that same amount, including a $275 million contract awarded last month.

Trump announced $274 million in funding for the Oroville Dam repairs last month.

Repairs are expected to take two years.