April 1997
Surface Water Supply Index Report

Provided by the US Natural Resources Conservation Service
Bozeman, Montana

The SWSI is designed for areas that rely primarily on snowmelt runoff as the primary source of surface water. The SWSI accounts for snowpack, mountain precipitation, streamflow, reservoir contents, and soil moisture conditions. The SWSI can be used by irrigators, fisheries personnel, recreationists, and others who utilize surface waters. SWSI values are categorized as follows:

IDBasin NameValue
1Marias Above Tiber Reservoir2.9
1Marias Above Tiber Reservoir2.9
2Tobacco3.6
2Tobacco3.6
3Kootenai to Libby Dam2.9
3Kootenai to Libby Dam2.9
4Kootenai River below Libby Dam2.3
4Kootenai River below Libby Dam2.3
5Fisher River3.8
5Fisher River3.8
6Yaak River3.5
6Yaak River3.5
7North FK. Flathead River3.7
7North FK. Flathead River3.7
8Middle FK. Flathead River3.6
8Middle FK. Flathead River3.6
9South FK. Flathead River3.6
9South FK. Flathead River3.6
10Flathead at Columbia Falls3.6
10Flathead at Columbia Falls3.6
11Stillwater/Whitefish Rivers3.7
11Stillwater/Whitefish Rivers3.7
12Swan River3.9
12Swan River3.9
13Flathead River at Polson3.6
13Flathead River at Polson3.6
14Mission Valley3.9
14Mission Valley3.9
15Little Bitterroot River3.5
15Little Bitterroot River3.5
16Clark above Missoula3.1
16Clark above Missoula3.1
17Blackfoot River3.2
17Blackfoot River3.2
18Clark Fork above Missoula3.1
18Clark Fork above Missoula3.1
19Bitterroot River3.8
19Bitterroot River3.8
20Clark Fork River below Bitterroot River3.3
20Clark Fork River below Bitterroot River3.3
21Clark Fork River below Flathead River3.5
21Clark Fork River below Flathead River3.5
22Beaverhead River2.7
22Beaverhead River2.7
23Ruby River3
23Ruby River3
24Big Hole River3.5
24Big Hole River3.5
25Boulder River (Jefferson)2.3
25Boulder River (Jefferson)2.3
26Jefferson River3.2
26Jefferson River3.2
27Madison River4
27Madison River4
28Gallatin River3.6
28Gallatin River3.6
29Missouri River above Canyon Ferry3.5
29Missouri River above Canyon Ferry3.5
30Missouri River below Canyon Ferry3.5
30Missouri River below Canyon Ferry3.5
31Smith River2.8
31Smith River2.8
32Sun River3.1
32Sun River3.1
33Teton River2.6
33Teton River2.6
34Birch/Dupuyer2.5
34Birch/Dupuyer2.5
36Musselshell River3.1
36Musselshell River3.1
37Missouri River above Fort Peck3.3
37Missouri River above Fort Peck3.3
38Missouri River below Fort Peck3.3
38Missouri River below Fort Peck3.3
39Milk River3.2
39Milk River3.2
41Yellowstone River above Livingston4
41Yellowstone River above Livingston4
42Shields River4
42Shields River4
43Boulder River (Yellowstone)3.6
43Boulder River (Yellowstone)3.6
44Stillwater River3.2
44Stillwater River3.2
45Rock/Red Lodge Creeks3.7
45Rock/Red Lodge Creeks3.7
46Clarks Fork River4
46Clarks Fork River4
47Yellowstone River above Bighorn River3.8
47Yellowstone River above Bighorn River3.8
48Bighorn River below Bighorn Lake3.6
48Bighorn River below Bighorn Lake3.6
49Little Bighorn River1.2
49Little Bighorn River1.2
50Yellowstone River below Bighorn River3.7
50Yellowstone River below Bighorn River3.7
51Tongue River1.3
51Tongue River1.3
52Powder River1.8
52Powder River1.8