DENVER (AP) — As floodwater started to rise Sept. 11, some gas and oil operators began shutting wells and securing facilities. It would be five days before state regulators announced their own plans.

“Did the state have a disaster plan for the oil and gas fields?” asked Bruce Baziel, energy program director of the environmental group Earthworks. “It was hard to tell.”

From the start, state gas and oil regulators were gathering information and passing it on to the incident commander overseeing disaster response, said Alan Gilbert, a Colorado Department of Natural Resources official.

“That’s our role as a technical agency,” Gilbert said.

Throughout the first flood weekend, oil companies provided information on their own operations to the Colorado Oil and Gas Conservation Commission.

“Demands on us to be transparent were high,” said Tisha Schuller, president of the Colorado Oil and Gas Association, an industry group.

Yet as pictures of bubbling pipes, spouting wells and floating tanks began to appear on social media, fears rose about what was happening in the flooded oil fields.

On Sept. 16, as the flood covered parts of the oil-rich Denver-Julesburg Basin, more steps to assess impacts were announced by the oil and gas commission staff.

“We intend to compile an ongoing spreadsheet with the status of operations,” said Matt Lepore, executive director of the commission.

Regulations require operators to report spills. Lepore asked for the industry’s voluntary cooperation in assessing the status of all wells.

“In the middle of a disaster, it strikes me that this ought to have been required,” said Peter May-smith, executive director of Conservation Colorado. “If it wasn’t required by regulation, the governor should have issued an executive order.”

The steps announced were “ad hoc,” but the commission was monitoring the situation, DNR’s Gilbert said.

“We are going to have a formal review,” Gilbert said. “We’ll look at what worked and what didn’t work.”

Within days, the commission had about 18 inspectors in the field checking sites. It used its mapping capabilities to identify wells and facilities in floodplains and focus on those. About 1,500 wells were identified in the floodplains of the South Platte and other Front Range rivers, Gilbert said.

“For years, conservation groups have pressed for limited drilling in floodplains, and the state and the industry have fought it,” said Gary Wockner, Colorado program director for Clean Water Action. “Part of this wasn’t a natural disaster but a man-made disaster.”

The industry estimated that at the height of the flooding, 1,900 wells were shut in. There are more than 20,000 wells in the basin.

State inspectors counted 14 “notable releases” primarily from overturned or damaged tanks, totaling 1,042 barrels (43,764 gallons) of petroleum products. There were 13 releases of produced water — which contains well impurities — totaling 430 barrels (18,060 gallons), according to the state.

“That’s thousands of gallons of pollutants poisoning our waterways,” Wockner said. “It isn’t something to be dismissed.”

By Thursday, Oct. 3, inspectors had covered 90 percent of the wells and facilities in the floodplains, Gilbert said.

“When you have an industrial activity of this scale, you need clear contingency plans,” said Conservation Colorado’s May-smith. “A clear plan in advance.”

State officials will review how effective regulations were in preventing flood spills and whether reporting and emergency plans were adequate, Gilbert said.

Could that lead to new rules or plans?

“That is what we are going to look at,” Gilbert said.

State and industry officials insist their performance was good.

“It was chaos — 11,000 homes, 200 miles of road, destroyed,” the Oil and Gas Association’s Schuller said. “You can’t plan for that. You just have to be flexible and responsive.”