This report is a compilation, for each of the seven Indian reservations in Montana, of the availability of hydrologic data. The report consists of an annotated bibliography of groundwater resources reports, selected data for wells and springs, and a listing of the availability of surface-water and water-quality data. 49°4 8°A LBERTA 115° 113 three samples of water were collected for chemical analysis at 11 sites on creeks, lakes, and drains in the project area. The onsite work upon which this report is based was done during the summer and fall of 1956; additional onsite work was done in 1957.]