July 1996
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
1Marias Above Tiber Reservoir2
2Tobacco3.8
2Tobacco3.8
3Kootenai to Libby Dam3.6
3Kootenai to Libby Dam3.6
4Kootenai River below Libby Dam1.5
4Kootenai River below Libby Dam1.5
5Fisher River2.4
5Fisher River2.4
6Yaak River2.7
6Yaak River2.7
7North FK. Flathead River2.8
7North FK. Flathead River2.8
8Middle FK. Flathead River2.4
8Middle FK. Flathead River2.4
9South FK. Flathead River2
9South FK. Flathead River2
10Flathead at Columbia Falls2.4
10Flathead at Columbia Falls2.4
11Stillwater/Whitefish Rivers3.1
11Stillwater/Whitefish Rivers3.1
12Swan River2.1
12Swan River2.1
13Flathead River at Polson2.4
13Flathead River at Polson2.4
14Mission Valley2
14Mission Valley2
15Little Bitterroot River2.9
15Little Bitterroot River2.9
16Clark above Missoula0.7
16Clark above Missoula0.7
17Blackfoot River1.6
17Blackfoot River1.6
18Clark Fork above Missoula1.2
18Clark Fork above Missoula1.2
19Bitterroot River2.1
19Bitterroot River2.1
20Clark Fork River below Bitterroot River1.4
20Clark Fork River below Bitterroot River1.4
21Clark Fork River below Flathead River2.1
21Clark Fork River below Flathead River2.1
22Beaverhead River1
22Beaverhead River1
23Ruby River1.9
23Ruby River1.9
24Big Hole River2.7
24Big Hole River2.7
25Boulder River (Jefferson)0.6
25Boulder River (Jefferson)0.6
26Jefferson River1.7
26Jefferson River1.7
27Madison River2.9
27Madison River2.9
28Gallatin River1.8
28Gallatin River1.8
29Missouri River above Canyon Ferry2.5
29Missouri River above Canyon Ferry2.5
30Missouri River below Canyon Ferry2.2
30Missouri River below Canyon Ferry2.2
31Smith River1.3
31Smith River1.3
32Sun River2.5
32Sun River2.5
33Teton River2.3
33Teton River2.3
34Birch/Dupuyer2.1
34Birch/Dupuyer2.1
36Musselshell River2
36Musselshell River2
37Missouri River above Fort Peck2.9
37Missouri River above Fort Peck2.9
38Missouri River below Fort Peck2.1
38Missouri River below Fort Peck2.1
39Milk River2.1
39Milk River2.1
41Yellowstone River above Livingston2.8
41Yellowstone River above Livingston2.8
42Shields River0.3
42Shields River0.3
43Boulder River (Yellowstone)2.4
43Boulder River (Yellowstone)2.4
44Stillwater River1.8
44Stillwater River1.8
45Rock/Red Lodge Creeks2.3
45Rock/Red Lodge Creeks2.3
46Clarks Fork River2.7
46Clarks Fork River2.7
47Yellowstone River above Bighorn River2.5
47Yellowstone River above Bighorn River2.5
48Bighorn River below Bighorn Lake1.5
48Bighorn River below Bighorn Lake1.5
49Little Bighorn River-0.5
49Little Bighorn River-0.5
50Yellowstone River below Bighorn River2.7
50Yellowstone River below Bighorn River2.7
51Tongue River-0.6
51Tongue River-0.6
52Powder River-0.7
52Powder River-0.7
999Kootenai at Ft. Steele2.2
999Kootenai at Ft. Steele2.2