The Big Grass Fire — which became Oregon's largest wildfire on record — is approaching full containment after scorching 578,637 acres across Malheur County, Oregon, and Owyhee County, Idaho. As of August 23, 2026, the fire has reached 93% containment, a significant milestone after weeks of extreme fire behavior that challenged firefighting resources across the region.

A Fire of Historic Scale

The Big Grass Fire ignited in late July along the rugged Oregon-Idaho border, fueled by bone-dry grass and brush, high temperatures, and gusty winds. At its peak, it was burning at a rate that outpaced suppression efforts on multiple fronts simultaneously. The fire drew international attention when it crossed 300,000 acres in early August — a threshold that placed it among the largest wildfires in the lower 48 states in recent decades.

By August 20, the fire had reached approximately 579,006 acres and was 85% contained. Crews spent the following days systematically securing and mopping up the remaining uncontrolled perimeter under progressively more favorable conditions. The Bureau of Land Management Boise District revised its Temporary Closure Order for the surrounding area on August 18 as containment improved.

What Made It So Large

The terrain where the Big Grass Fire burned — a vast expanse of sagebrush-steppe in the high desert along the Oregon-Idaho border — is ideally suited for rapid fire spread. Characterized by:

  • Continuous, fine fuel loads (native grasses and forbs that cured early due to drought)
  • Flat to gently rolling terrain with few natural firebreaks
  • Persistent afternoon winds that regularly exceeded 20 mph
  • Limited access roads for ground crews and equipment

Under such conditions, fire can travel miles in hours. Aerial resources — including air tankers and helicopters — were critical in slowing the fire's spread and protecting key values.

Ecological Impact

The vast burn scar across Malheur and Owyhee counties represents a significant ecological event for the Great Basin sagebrush ecosystem. Post-fire assessments will evaluate the extent of damage to sage-grouse habitat, as well as the risk of invasive species — particularly cheatgrass — colonizing burned areas. Cheatgrass is highly flammable and can dramatically increase future fire risk if it becomes dominant in the post-fire landscape.

Range managers and ecologists from the BLM and USDA Natural Resources Conservation Service are expected to begin post-fire rapid assessments once suppression operations are fully wound down.

Looking Ahead

With containment at 93%, crews are focused on mop-up operations — extinguishing smoldering material within the fire's perimeter to prevent reignition if wind events occur. The BLM has indicated that full containment is expected within the next several days, barring significant weather changes.

For ranchers and landowners in the affected area, the BLM Boise District and Oregon Department of Agriculture are working to coordinate post-fire rangeland recovery assistance. Those with questions about closure orders or recovery programs can contact the BLM Vale District Office at (541) 473-3144.