National Water-Quality Assessment Program
Drainage-area boundaries for selected sampling stations, scale 1:100,000, Yellowstone River Basin, Montana, North Dakota, and Wyoming, Version 2.0, by Ronald B. Zelt
Yellowstone River Basin study unit boundary, National Water-Quality Assessment Program, scale 1:100,000, Montana, North Dakota, and Wyoming, by Ronald B. Zelt
Surface-water sampling stations, National Water-Quality Assessment, Yellowstone River Basin by Ronald B. Zelt
Drainage-area boundaries for selected sampling stations, scale 1:100,000, Yellowstone River Basin, Montana, North Dakota, and Wyoming,Version 1.2, by Ronald B. Zelt and Laura L. Hallberg