1.  Except as otherwise provided in subsection 3, the boards of county commissioners of the counties of this state may, by ordinance regularly enacted, regulate, control and prohibit, as a public nuisance, the excessive emission of dense smoke and air pollution caused by excessive soot, cinders, fly ash, dust, noxious acids, fumes and gases within the boundaries of the county.

2.  If an ordinance adopted pursuant to subsection 1 involves or affects agricultural operations, any plan or program to carry out that ordinance must allow for customarily accepted agricultural practices to occur on agricultural land. A governmental entity which is considering the adoption of such a plan or program shall consult with the State Department of Agriculture or local conservation districts to determine the customarily accepted agricultural practices that may be affected by the proposed plan or program.

3.  An existing compliance schedule, variance order or other enforcement action relating to air pollution by fossil fuel-fired steam generating facilities, with a capacity greater than 1,000 megawatts, may not be enforced until July 1, 1977.