All reservations of oil and gas and other mineral rights and sales of previously reserved oil and gas and other mineral rights in county lands made or entered into by any county prior to May 20, 1949, acting by its board of county commissioners, all leases of oil and gas or rights, and all unit agreements relating to or dealing with oil and gas and containing provisions similar to those set forth in section 30-11-304, affecting county lands, made or entered into by any county prior to May 20, 1949, acting by its board of county commissioners are hereby confirmed, validated, and declared to be legal and valid in all respects.
C.R.S. § 30-11-305