This collection is a subgroup (Predecessor Agency) of the Montana Public Service Commission records, RS 501. The Board of Railroad Commissioners, predecessor agency to the PSC, served ex-officio as the Montana Irrigation Commission from 1919 until it was abolished in 1929. Please see the primary finding aid for more Montana Public Service Commission records.

This collection consists predominantly of subject files (1919-1929) for irrigation districts around the state. The files include correspondence, petitions, legal documents, court papers, reports, and maps concerning the founding of the districts, plans for their developments, reports on their feasibility, and engineering reports. There are also project histories, arranged by district number; and project surveys arranged by county.