The state and federal governments ignored concerns about the inadequacy of the spillway system at Lake Oroville more than a decade ago because the fix was too expensive.

Well, like the old TV commercial for oil filters said, “You can pay me now or pay me later.”

The state government, which operates the dam, will be paying later and the federal government, who approves hydroelectric projects like Oroville, will be chipping in as well.

How much is anybody’s guess. The state Department of Water Resources, pressed for a figure by reporters, estimated the cost to fix the crumbling spillway at the country’s tallest dam at $100 million to $200 million. That’s strictly a guess because it’s far too early to tell the extent of the eventual damage.

Like the DWR’s prediction Friday that the emergency spillway wouldn’t be needed, we think the math is way off. It wouldn’t surprise us if the bill for this whole chaotic episode comes to a half billion dollars.

The extent of damage to the disintegrating spillway is still unknown. Releases were ramped up Sunday when it appeared the northern rim of the dam — the part above the emergency spillway — was in danger of collapsing. Dam operators sent more water down the regular spillway even though it’s been falling apart all week. Damaging that spillway was more palatable than the prospect of seeing the emergency spillway undercut the dam and collapse the rim.

Now the DWR needs to drain the lake a bit so it can shut off the regular spillway long enough to assess the damage and engineer a fix. That work likely can’t be done until May or June. Because of all the snowmelt anticipated this spring, the spillway will be needed for a while.

The reconstruction of the spillway will need to be a rush job, completed by fall. The urgent timetable will drive up the price.

Then there’s the emergency spillway. Until Saturday it had never been used. Now it’s forever changed. As we’ve said before, it’s not a spillway at all. It’s a hillside that was filled with rocks and trees. That hillside is now scarred, dredged to the bedrock in spots by a flow equal to that of the Sacramento River in Butte County in summer.

The state cannot repair the damage and restore the hillside to a pristine condition, so it should do what should have been done and line the ravine with concrete to handle emergency runoff without erosion.

That will add more millions to the tab.

Then there’s the cost of the response already. There were an amazing number of workers brought in for various aspects of the emergency. There were state workers monitoring the damage and others devising plans for how to deal with it. There were helicopters removing electric transmission lines and people on the ground securing towers. There were crews trying to clear out the hillside that would become the emergency spillway, working for two days to clear trees and brush so that the vegetation didn’t all get washed to the bottom and become a dam on the river. And after Saturday’s overflow, there were huge tractors working opposite the spillway, cutting a road so they could get the tractors down to the water’s edge and dig all the debris out of the spillway pool.

It’s safe to say that even during the worst summer wildfire, we don’t see this many helicopters in Butte County. Those cost money.

Now the Federal Energy Regulatory Commission, the same body that ignored concerns about the emergency spillway more than a decade ago, wants an independent review of the cause and the fix. Now FERC is concerned about oversight? It’s too little, too late.

Then there are the other costs, those borne by 180,000 evacuees who have been displaced because of a lack of maintenance and foresight. They have a right to be the most furious of all.