August 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 Reservoir1.8
1Marias Above Tiber Reservoir1.8
2Tobacco2
2Tobacco2
3Kootenai to Libby Dam2.4
3Kootenai to Libby Dam2.4
4Kootenai River below Libby Dam0.7
4Kootenai River below Libby Dam0.7
5Fisher River3
5Fisher River3
6Yaak River2.6
6Yaak River2.6
7North FK. Flathead River1.7
7North FK. Flathead River1.7
8Middle FK. Flathead River1.7
8Middle FK. Flathead River1.7
9South FK. Flathead River1.4
9South FK. Flathead River1.4
10Flathead at Columbia Falls1.6
10Flathead at Columbia Falls1.6
11Stillwater/Whitefish Rivers2.1
11Stillwater/Whitefish Rivers2.1
12Swan River0.9
12Swan River0.9
13Flathead River at Polson1.5
13Flathead River at Polson1.5
14Mission Valley2.2
14Mission Valley2.2
15Little Bitterroot River3.5
15Little Bitterroot River3.5
16Clark above Missoula2.7
16Clark above Missoula2.7
17Blackfoot River2.6
17Blackfoot River2.6
18Clark Fork above Missoula2.7
18Clark Fork above Missoula2.7
19Bitterroot River3.2
19Bitterroot River3.2
20Clark Fork River below Bitterroot River2.8
20Clark Fork River below Bitterroot River2.8
21Clark Fork River below Flathead River1.9
21Clark Fork River below Flathead River1.9
22Beaverhead River1.4
22Beaverhead River1.4
23Ruby River1.8
23Ruby River1.8
24Big Hole River2.4
24Big Hole River2.4
25Boulder River (Jefferson)2.3
25Boulder River (Jefferson)2.3
26Jefferson River1.8
26Jefferson River1.8
27Madison River1.2
27Madison River1.2
28Gallatin River1.6
28Gallatin River1.6
29Missouri River above Canyon Ferry1.4
29Missouri River above Canyon Ferry1.4
30Missouri River below Canyon Ferry1.7
30Missouri River below Canyon Ferry1.7
31Smith River2.9
31Smith River2.9
32Sun River2.1
32Sun River2.1
33Teton River1.5
33Teton River1.5
34Birch/Dupuyer1.5
34Birch/Dupuyer1.5
36Musselshell River3.6
36Musselshell River3.6
37Missouri River above Fort Peck3.4
37Missouri River above Fort Peck3.4
38Missouri River below Fort Peck2.5
38Missouri River below Fort Peck2.5
39Milk River1.3
39Milk River1.3
41Yellowstone River above Livingston2.5
41Yellowstone River above Livingston2.5
42Shields River3
42Shields River3
43Boulder River (Yellowstone)2.7
43Boulder River (Yellowstone)2.7
44Stillwater River2.4
44Stillwater River2.4
45Rock/Red Lodge Creeks2.2
45Rock/Red Lodge Creeks2.2
46Clarks Fork River2.5
46Clarks Fork River2.5
47Yellowstone River above Bighorn River2.5
47Yellowstone River above Bighorn River2.5
48Bighorn River below Bighorn Lake1.8
48Bighorn River below Bighorn Lake1.8
49Little Bighorn River2.7
49Little Bighorn River2.7
50Yellowstone River below Bighorn River1.9
50Yellowstone River below Bighorn River1.9
51Tongue River-0.8
51Tongue River-0.8
52Powder River2.9
52Powder River2.9
999Kootenai at Ft. Steele-0.1
999Kootenai at Ft. Steele-0.1