(a) Prohibitions. Surface coal mining and reclamation operations shall not: (1) Interrupt, discontinue, or preclude farming on alluvial valley floors; or (2) cause material damage to the quantity or quality of water in surface or underground water systems that supply alluvial valley floors.

(b) Statutory exclusions. The prohibitions of paragraph (a) of this section shall not apply—

(1) Where the premining land use of an alluvial valley floor is undeveloped rangeland which is not significant to farming;

(2) Where farming on the alluvial valley floor that would be affected by the surface coal mining operation is of such small acreage as to be of negligible impact on the farm's agricultural production;

(3) To any surface coal mining and reclamation operation that, in the year preceding August 3, 1977—

(i) Produced coal in commercial quantities and was located within or adjacent to an alluvial valley floor; or

(ii) Obtained specific permit approval by the State regulatory authority to conduct surface coal mining and reclamation operations within an alluvial valley floor; or

(4) To any land that is the subject of an application for renewal or revision of a permit issued pursuant to the Act which is an extension of the original permit, insofar as: (i) The land was previously identified in a reclamation plan submitted under either part 780 or 784 of this chapter, and (ii) the original permit area was excluded from the protection of paragraph (a) of this section for a reason set forth in paragraph (b)(3) of this section.