A big Butte County walnut rancher has filed a $15.45 million claim against the state Department of Water Resources, alleging the agency is responsible for damage suffered after the Oroville spillway emergency in February.

JEM Farms and Chandon Ranch -- jointly owned properties that straddle the Feather River 17 miles below Oroville Dam -- say they lost a total of 27 acres of land because of the way the water agency maintained and operated the spillway before, during and after the February crisis.

"Our investigation shows the Department of Water Resources failed to address a known hazard, and made only Band-Aid repairs," attorney Niall McCarthy of Burlingame-based Cotchett, Pitre & McCarthy said in a statement. “For years, the State of California knew the gated spillway would fail, but chose to roll the dice with the safety and property of the residents of Oroville.”

Large water releases at the height of the incident were followed by an abrupt reduction of flows on Feb. 27, leading to widespread bank collapses downstream from the dam.

As land collapsed on the two farm properties -- the parcels total 2,000 acres, with JEM having 4 miles of frontage on the river's east bank, Chandon three-quarters of a mile on the west -- sections of their walnut orchards dropped into the river, too.

The claim calculates the value of the lost 27 acres at $1.08 million -- $40,000 an acre -- and losses of future walnut production over the next 50 years at about $14 million. The action also seeks $200,000 for cleaning up the mess left behind by the rapidly fluctuating river levels.

"Normally, they raise (the river) up incrementally and they let it down incrementally," George Onyett, who has managed JEM Farms for 41 years, said in a phone interview Thursday. "This was just one fell swoop -- the river went down about 8 feet when they shut the spillway off."

The Department of Water Resources did not respond to a request for comment on the claim. The agency said earlier this year that heavy winter rainfall, not its releases, was the likely culprit for the erosion.

“We’ve received over a year’s worth of rain in two months,” Lauren Bisnett, a DWR spokeswoman, told the Los Angeles Times in March. “It’s not uncommon to see erosion in that region.”

Lawyers for businesses and residents in and around Oroville say they're preparing similar claims against the state ... to meet a six-month deadline that arrives this month.

The actions are the first step in a process that will likely result in the state rejecting the claims and the filing of lawsuits against the Department of Water Resources.