Colo. Const. art. XXVI, § 2
Before the emplacement of any nuclear explosive device in the ground in this state, the detonation of that device shall first have been approved by the voters through enactment of an initiated or referred measure authorizing that detonation, such measure having been ordered, proposed, submitted to the voters, and approved as provided in section 1 of article V of this constitution.
Source: L. 74: Entire article was added, effective upon proclamation of the Governor, December 20, 1974, but does not appear in the session laws.