UPDATE 9/15/2013 10:30 ET: A federal forestry official said investigators found no evidence of an illegal grow at the fire's place of origin.
The scope and speed of the Yosemite Rim Fire can be blamed on all sorts of human activity, from twentieth-century logging activity to climate change. The massive blaze is now 80 percent contained, but the nature of the spark that ignited it remains unknown.
In a video posted to Youtube last week, Chief Todd McNeal of the Twain Harte Fire Department speculated that humans were probably behind the fire's origin, too, as no lightning occurred in the area. And, he added, officials "highly suspect" that the source was an illegal marijuana farm.
No officials will back up McNeal's claim, the Associated Press reports, and he hasn't provided any further explanation for why pot growers are suspected. It could just be that they're usually the source of trouble in the region:
Illegal marijuana grows in national parks and forests have tormented federal land managers for years. Growers hike into remote canyons with poisons and irrigation lines and set up camp for months. The poisons kill wildlife and seep into streams and creeks. The growers leave tons of garbage behind.
Starting the fourth-largest wildfire in California's history is just one more addition to their rap sheet.