March 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 Reservoir2.8
1Marias Above Tiber Reservoir2.8
2Tobacco3
2Tobacco3
3Kootenai to Libby Dam1.5
3Kootenai to Libby Dam1.5
4Kootenai River below Libby Dam1.3
4Kootenai River below Libby Dam1.3
5Fisher River1.3
5Fisher River1.3
6Yaak River3.3
6Yaak River3.3
7North FK. Flathead River3.5
7North FK. Flathead River3.5
8Middle FK. Flathead River3.3
8Middle FK. Flathead River3.3
9South FK. Flathead River3.3
9South FK. Flathead River3.3
10Flathead at Columbia Falls3.4
10Flathead at Columbia Falls3.4
11Stillwater/Whitefish Rivers3.2
11Stillwater/Whitefish Rivers3.2
12Swan River3.8
12Swan River3.8
13Flathead River at Polson3
13Flathead River at Polson3
14Mission Valley3.9
14Mission Valley3.9
15Little Bitterroot River3.3
15Little Bitterroot River3.3
16Clark above Missoula3.2
16Clark above Missoula3.2
17Blackfoot River3
17Blackfoot River3
18Clark Fork above Missoula3.1
18Clark Fork above Missoula3.1
19Bitterroot River3.7
19Bitterroot River3.7
20Clark Fork River below Bitterroot River3.2
20Clark Fork River below Bitterroot River3.2
21Clark Fork River below Flathead River3.1
21Clark Fork River below Flathead River3.1
22Beaverhead River3.2
22Beaverhead River3.2
23Ruby River3.3
23Ruby River3.3
24Big Hole River3.4
24Big Hole River3.4
25Boulder River (Jefferson)3.2
25Boulder River (Jefferson)3.2
26Jefferson River3.4
26Jefferson River3.4
27Madison River4
27Madison River4
28Gallatin River4
28Gallatin River4
29Missouri River above Canyon Ferry3.7
29Missouri River above Canyon Ferry3.7
30Missouri River below Canyon Ferry3.7
30Missouri River below Canyon Ferry3.7
31Smith River3.3
31Smith River3.3
32Sun River2.6
32Sun River2.6
33Teton River2.1
33Teton River2.1
34Birch/Dupuyer2.7
34Birch/Dupuyer2.7
36Musselshell River2.8
36Musselshell River2.8
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 River2.9
39Milk River2.9
41Yellowstone River above Livingston4
41Yellowstone River above Livingston4
42Shields River4
42Shields River4
43Boulder River (Yellowstone)4
43Boulder River (Yellowstone)4
44Stillwater River4
44Stillwater River4
45Rock/Red Lodge Creeks4
45Rock/Red Lodge Creeks4
46Clarks Fork River4
46Clarks Fork River4
47Yellowstone River above Bighorn River4
47Yellowstone River above Bighorn River4
48Bighorn River below Bighorn Lake3.6
48Bighorn River below Bighorn Lake3.6
49Little Bighorn River1.4
49Little Bighorn River1.4
50Yellowstone River below Bighorn River3.8
50Yellowstone River below Bighorn River3.8
51Tongue River1.6
51Tongue River1.6
52Powder River2.1
52Powder River2.1