Wyo. Stat. § 31-18-708: Persons rendering emergency assistance exempt from civil liability.

(a) Any person who provides assistance or advice without compensation other than reimbursement of out-of-pocket expenses in mitigating or attempting to mitigate the effects of an actual or threatened discharge of hazardous materials, or in preventing, cleaning up or disposing of or in attempting to prevent, clean up or dispose of any discharge of hazardous materials, is not liable for any civil damages for acts or omissions in good faith in providing the assistance or advice. This immunity does not apply to acts or omissions constituting gross negligence or willful or wanton misconduct. As used in this subsection:

(i) "Discharge" includes leakage, seepage or other release;

(ii) "Hazardous materials" includes all materials and substances which are now or hereafter designated or defined as hazardous by any state or federal law or by the regulations of any state or federal government agency.