C.R.S. § 36-20-109

(1) No person may engage in activities for weather modification and control without a weather modification permit issued by the director; nor may any person engage in any activities in violation of any term or condition of the permit. (2) The director, to the extent he considers exemptions practical, may provide by regulation for exempting the following activities from the fee requirements of this article: (a) Research, development, and experiments conducted by state and federal agencies, state institutions of higher education, and bona fide nonprofit research organizations; (b) Laboratory research and experiments; and (c) Activities of an emergency nature for protection against fire, frost, hail, sleet, smog, fog, or drought.