44 CFR §204.21

1. (a)Determinations. FEMA will approve declarations for fire management assistance when the Administrator determines that a fire or fire complex on public or private forest land or grassland threatens such destruction as would constitute a major disaster.
2. (b)Evaluation criteria. FEMA will evaluate the threat posed by a fire or fire complex based on consideration of the following specific criteria:
   1. (1)Threat to lives and improved property, including threats to critical facilities/infrastructure, and critical watershed areas;
   2. (2)Availability of State and local firefighting resources;
   3. (3)High fire danger conditions, as indicated by nationally accepted indices such as the National Fire Danger Ratings System;
   4. (4)Potential major economic impact.