The president of a group dedicated to fishing and preserving New Mexico's trout waters couldn't believe what he was seeing.

The tanker truck's back wheels slipped into the soft dirt as it was trying to turn around on a dirt road. It rolled onto its side with its top latch open and thousands of gallons of an oily, hot asphalt mixture went spilling out. The sludge flowed down the drainage from the road toward the Rio de Las Vacas, a popular fishing and recreation spot in the Santa Fe National Forest.

Rudy Rios, president of New Mexico Trout, said Tuesday's rollover was an accident but it — and the damage to the river — could have been prevented.

"It was the inefficiency of government at play," he said of the scene after the spill. "Nobody wanted to take responsibility. Everybody was looking at everybody else to make a decision."

Rios was concerned that the truck driver had no assistance, the lid to the tanker was not locked and it look some time before highway crews brought up any help from the resurfacing project just a half-mile down the road. By then, the sludge had reached the river, he said.

Now, state and federal environment officials are trying to determine the extent of the damage.

Water and soil samples were taken Wednesday, and investigators with state police and the New Mexico Motor Transportation Division were investigating the actions of the trucking company, Arizona based-Cactus Transport Inc.

An employee at the company's office in Albuquerque declined to comment, and messages left for the operations manager at the company's headquarters were not immediately returned.

The driver of the tanker truck suffered minor injuries, police said. His name was not released.

State Police Lt. Eric Garcia said enforcement action will be taken against the company but not until investigators with the New Mexico Environment Department and the Environmental Protection Agency finish assessing the damage.

"It's not a major mess, it's nothing like BP," Garcia said, referring to the oil well blowout in the Gulf of Mexico. "But it was a spill and it was contamination and it's something we're going to have to deal with accordingly."

The 5,000-gallon tanker had sprayed some of its load on the N.M. 126 resurfacing project before getting tangled up, so it's unclear exactly how many gallons reached the river. It appeared most of the load leaked out by the time the tanker was righted, Garcia said.

Rios, who happened to be in the area for a construction job, said he helped the driver and asked a Forest Service worker who also witnessed the accident to request a front-end loader from the road crew nearby. No loader ever showed up, and Rios said it look some time to persuade one of the crew supervisors to bring in gravel to dam up what was left of the spill.

"The emulsion was breaking down and yellow gunk was just oozing down the river," Rios said. "It looked like a chemical spill in the river."

New Mexico Transportation Department spokesman Mark Slimp said highway crews at the site tried to help, but the agency doesn't have a plan for when vendors have an accident.

Forest Service employees also tried to use straw bales to soak up some of the spill.

Marcy Leavitt, head of New Mexico's Water and Waste Management Division, said the immediate focus is to clean up the black sludge from the drainage above Rio de Las Vacas to avoid having more of it leach into the river. Because there is a culvert under the road where the truck overturned, officials are concerned that rain runoff could push more of the contaminants into the river, she said.

"Right now, we need to focus on trying to get the soil cleaned up," Leavitt said.

The spill along Rio de Las Vacas comes just two weeks after two train tanker cars derailed, spilling fuel oil near Bosque del Apache National Wildlife Refuge along the Rio Grande in central New Mexico. Leavitt said spills typically happen along main roads, not in remote areas like the refuge or the foothills of the San Pedro Mountains.