As much as 4,000 gallons of diesel fuel spilled into the Colorado River in rural La Paz County, Ariz., on Saturday, prompting a joint effort by Arizona and California authorities to keep the fuel out of the Imperial Dam.
The dam feeds river water into the All-American Canal, the water source for the Imperial Valley.
The diesel fuel spilled from a pipeline on the river's edge across from the northeast corner of Imperial County.
Imperial County Supervisor Wally Leimgruber was on the scene Saturday following the spill, which occurred about 6:30 a.m.
Leimgruber said the spill was spotted by Arizona Department of Fish and Game officials.
Authorities first noticed a filmy substance flowing down river, he said. They investigated and determined it was diesel fuel.
Leimgruber said authorities managed to stop the leak but not before as much as 4,000 gallons of fuel entered the river.
The concern was the fuel, which does not mix with the water but evaporates, was flowing south toward the Imperial Dam.