March 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 Reservoir2.2
1Marias Above Tiber Reservoir2.2
2Tobacco2.5
2Tobacco2.5
3Kootenai to Libby Dam2.4
3Kootenai to Libby Dam2.4
4Kootenai River below Libby Dam2.6
4Kootenai River below Libby Dam2.6
5Fisher River1.1
5Fisher River1.1
6Yaak River1.4
6Yaak River1.4
7North FK. Flathead River2.2
7North FK. Flathead River2.2
8Middle FK. Flathead River2
8Middle FK. Flathead River2
9South FK. Flathead River2.2
9South FK. Flathead River2.2
10Flathead at Columbia Falls2.1
10Flathead at Columbia Falls2.1
11Stillwater/Whitefish Rivers2.8
11Stillwater/Whitefish Rivers2.8
12Swan River2
12Swan River2
13Flathead River at Polson2.4
13Flathead River at Polson2.4
14Mission Valley1.6
14Mission Valley1.6
15Little Bitterroot River0.3
15Little Bitterroot River0.3
16Clark above Missoula1.2
16Clark above Missoula1.2
17Blackfoot River1.6
17Blackfoot River1.6
18Clark Fork above Missoula1.4
18Clark Fork above Missoula1.4
19Bitterroot River3.1
19Bitterroot River3.1
20Clark Fork River below Bitterroot River2
20Clark Fork River below Bitterroot River2
21Clark Fork River below Flathead River2.5
21Clark Fork River below Flathead River2.5
22Beaverhead River2.9
22Beaverhead River2.9
23Ruby River0.6
23Ruby River0.6
24Big Hole River3.2
24Big Hole River3.2
25Boulder River (Jefferson)0.8
25Boulder River (Jefferson)0.8
26Jefferson River2.5
26Jefferson River2.5
27Madison River2.4
27Madison River2.4
28Gallatin River1.8
28Gallatin River1.8
29Missouri River above Canyon Ferry2.4
29Missouri River above Canyon Ferry2.4
30Missouri River below Canyon Ferry2
30Missouri River below Canyon Ferry2
31Smith River1.7
31Smith River1.7
32Sun River2
32Sun River2
33Teton River2
33Teton River2
34Birch/Dupuyer2.6
34Birch/Dupuyer2.6
36Musselshell River2
36Musselshell River2
37Missouri River above Fort Peck2.6
37Missouri River above Fort Peck2.6
38Missouri River below Fort Peck2
38Missouri River below Fort Peck2
39Milk River0.7
39Milk River0.7
41Yellowstone River above Livingston3.4
41Yellowstone River above Livingston3.4
42Shields River0.9
42Shields River0.9
43Boulder River (Yellowstone)2.2
43Boulder River (Yellowstone)2.2
44Stillwater River2.1
44Stillwater River2.1
45Rock/Red Lodge Creeks3
45Rock/Red Lodge Creeks3
46Clarks Fork River3.2
46Clarks Fork River3.2
47Yellowstone River above Bighorn River3.1
47Yellowstone River above Bighorn River3.1
48Bighorn River below Bighorn Lake2.1
48Bighorn River below Bighorn Lake2.1
49Little Bighorn River-0.3
49Little Bighorn River-0.3
50Yellowstone River below Bighorn River2.8
50Yellowstone River below Bighorn River2.8
51Tongue River0.5
51Tongue River0.5
52Powder River-0.4
52Powder River-0.4