DENVER - Colorado's flooding shut down hundreds of natural gas and oil wells in the state's main petroleum-producing region, triggering at least two spills, temporarily suspending a multibillion-dollar drilling frenzy and sending inspectors into the field to gauge the extent of pollution.
Besides the possible environmental impact, flood damage to roads, railroads and other infrastructure will affect the region's energy production for months to come. And analysts warn that images of flooded wellheads from the booming Wattenberg field will increase public pressure to impose restrictions on drilling techniques such as fracking.
"There's been massive amounts of growth in the last two years and it's certainly expected to continue," Caitlyn McCrimmon, a senior research associate for Calgary-based energy consultant ITG Investment Research, said of Colorado oil and gas drilling. "The only real impediment to growth in this area would be if this gives enough ammunition to environmentalists to rally support for fracking bans, which they had started working on before this.
Two spills were reported by Anadarko Petroleum Corp. -- 323 barrels (13,500 gallon) along the St. Vrain River near Platteville, and 125 barrels (5,250 gallons) into the South Platte River near Milliken, federal and state regulators said
In both cases, the oil apparently was swept away by floodwaters. Both releases involved condensate, a mixture of oil and water, said Environmental Protection Agency spokesman Matthew Allen.
Anadarko workers had tried to contain the South Platte spill by putting absorbent booms in the water, but state officials said only residual oil was collected.
"We're on that location and recovering what we can," company spokesman John Christiansen said Thursday, adding the company was still trying to reach other well sites rendered inaccessible by the flooding.
More reports of problems in northern Colorado's oil patch could emerge once flood waters recede and inspectors can access more sites, Allen said.
The Colorado Oil and Gas Conservation Commission also found some tanks that shifted or moved off pads but said most tanks and well pads were intact.
The EPA flew its first reconnaissance mission over the some of the most heavily damaged areas inside the flood zone Wednesday, once aircraft no longer were needed for search and rescue work. More flights were planned Thursday.
The state's northern plains took the brunt of the flooding after record rains pounded the Rocky Mountain foothills to the west. The area is home to Colorado's top oil patch, the Denver-Julesburg Basin, which includes the Wattenberg Field.
The once largely rural area has become more populated as the state has grown. As drilling has moved closer to homes and schools, many residents there have been pushing for more government oversight of drillers
The area was hit hard after water that flooded canyons in the foothills drained out onto the plains and into the South Platte River. The river where the larger spill occurred, the St. Vrain, feeds into the South Platte, which flows across the plains and into Nebraska.
Nearly 1,900 wells were initially shut down by the flood, out of more than 51,000 statewide. No major well spills have been reported, according to the Colorado Oil and Gas Association, an industry group. It says there was no known hydraulic fracturing going on at the time of the flooding.
The largest producer in the basin, Houston-based Noble Energy, said two wells that were releasing natural gas have been shut down and a third would be shut down once it was safe to access the well. The company estimates that it has shut down between 5 and 10 percent of its wells because of flooding and has been monitoring them from the air and ground.
The Colorado boom has been welcomed by many -- and opposed by many concerned about the possible environmental effects of fracking, a process that breaks apart deep rock to recover more gas.
If flood damage is minimal, the industry could quickly resume a frenzied pace of drilling in an area where companies were on track to sink $4 billion into new projects this year, McCrimmon said.
The price of natural gas rose 20 cents this week at hubs in Colorado after the wells closed, said Stephen Schork, an energy analyst and editor of The Schork Report. Natural gas supplies were already tight in northern California because wells were shut down by the Rim Fire that raged in and around Yosemite National Park, so Schork thinks a lack of production in Colorado could possibly lead to higher costs for gas-fired power plants.
McCrimmon said she expected the consequences will be negligible on broader oil and gas markets. Despite its growth, the Wattenberg Field ranks far behind other active oil plays in the U.S.
Colorado produced 135,000 barrels of oil a day in 2012, the highest level in at least three decades but still only about 2 percent of total U.S. production.
Colorado's natural gas production topped 1.6 trillion cubic feet in 2011, according to the Energy Information Administration. That's about 6 percent of the nation's total.
Denver-based PDC Energy, Texas-based Anadarko and Canada-based Encana Corp. also shut down wells but planned to reopen some of them.
Anadarko's Christiansen said a 4-inch natural gas pipeline began leaking late last week after the ground washed away around it. Christiansen said the pipeline was shut down and the leak was contained.
Encana said it resumed operations on more than 150 wells after shutting down almost 400 due to high water and poor access. That left 245 wells still out of service by mid-week, and inspections for environmental damage were continuing.