Humboldt County Sheriff’s Office press release:

The Kneeland-Greenwood Heights area is primarily all private property. Trespassing is a crime and trespassers could be subject to citation or arrest. 

Snow seekers should utilize the Horse Mountain, Six Rivers National Forest areas for recreational activity. If you do plan to recreate in the snow, please notify family and friends of where you are going and bring appropriate safety equipment in case you become lost, injured or stuck. Make sure your cell phone is charged if you bring one with you and have appropriate winter clothing.