New Mexico wildfire burn scar has forest officials worried

SANTA FE, New Mexico－As more than 3,000 firefighters in northern New Mexico continued to battle the United States' largest active wildfire on Sunday, federal forest officials are worried about future flash floods, landslides and destructive ash from the burn scar.

The 7-week-old fire, the largest in New Mexico's history, remained 50 percent contained after charring 1,274 square kilometers in rugged terrain east of Santa Fe.

Two planned burns merged to form the massive blaze at the southern tip of the Rocky Mountains in the Sangre de Cristo range.

One of the fires was previously traced to April 6, when a planned burn set by US Forest Service firefighters to clear out small trees and brush was declared out of control.

On Friday, investigators said they tracked the source of the second fire to the remnants of a planned January burn that lay dormant through several snowstorms only to flare up again last month.

Firefighting costs already surpass $132 million, climbing by $5 million a day, authorities said.

Micah Kiesow, team leader and a soil and watershed program manager with the Santa Fe National Forest, said steep mountain slopes had acted like a sponge before the fire.

"Post-fire in some of these areas, especially the high soil burn severity areas and the moderate, we're looking at now a steep slope that's more like a parking lot," Kiesow told the Santa Fe New Mexican.

He said that could signal an "extreme change in watershed response" during the monsoon season.

Flooding presents another problem for communities near burn scars with ash flowing into rivers and streams.

Many water treatment facilities are not equipped for the expensive, time-intensive process of filtering ash. Experts say ash and debris can harm water quality with high levels of nitrates and phosphorus.

A hazard assessment from the Forest Service and US Geological Survey showed that some burned areas on the New Mexico fire could see heavy debris flows if they receive 6 millimeters of rain in 15 minutes.

Initial estimates show that the fire has destroyed at least 330 homes, but state officials expect the number of homes and other structures that have burned to rise to more than 1,000 as more assessments are done.