DENVER — Coloradans watched for more spills in flooded oilfields as crews waited for the waters to recede so they could begin cleanup operations.
Four new spills were discovered Friday, including 2,400 gallons of oil from a toppled storage tank and almost 900 gallons from an unspecified source. Oil spilled from two other damaged tanks but authorities did not know how much.
That brings the known volume of oil released since massive flooding began last week along Colorado's Front Range to an estimated 22,060 gallons or about 525 barrels.
Most of the oil releases reported to date came from tanks operated by Texas-based Anadarko Petroleum Co. At least four of the releases reported by the company were in Weld County and spilled oil into the South Platte River or a tributary, according to information submitted to regulators.
Other companies might have suffered similar problems since flooding began last week, but they have not yet been able to assess their damage.
An aerial survey of the flood area on Thursday revealed up to two dozen overturned oil storage tanks, state regulators said. Releases from those tanks could not be immediately confirmed.
With many roads in the area washed out, the sites remained largely inaccessible, preventing cleanup work from getting underway, said Anadarko spokesman John Christiansen.
"We've got a couple of amphibious vehicles and flat-bottom boats that we're using, but really until things have a chance to dry out and some of the infrastructure issues are sorted out, it's going to be difficult," Christiansen said.
Authorities in Weld County have said their concern over spilled oil is eclipsed by much greater volumes of sewage and other contaminants washing into local waterways.
In other developments:
— The number of people unaccounted for dropped to around 80 thanks to door-to-door searches and restored communications. Seven people have died and three others are missing and presumed dead.
— The Federal Emergency Management Agency has approved $8 million in aid for homeowners and the number of FEMA personnel on the ground increased from 250 to 800.
— Larimer County Sheriff Justin Smith said he was heartened to see residents in remote communities doing their own makeshift repairs to roads.
— The new official in charge of recovery efforts, IHS Inc. executive chairman Jerre Stead, said his priorities are rebuilding the affected area equal or better than it was before.
— Gov. John Hickenlooper approved another $20 million in emergency flood funding, bringing the total to $26 million, and expanded the disaster zone to include a total of 17 counties.
— Schools are making arrangements for students in flooded towns to head back to class. Students in Lyons will attend school in nearby Longmont starting next week while students in another mountain town may have a teacher sent to them.
Brown reported from Billings, Mont.