February 2009
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 Reservoir-1.4
1Marias Above Tiber Reservoir-1.4
2Tobacco-1.1
2Tobacco-1.1
3Kootenai to Libby Dam-2.1
3Kootenai to Libby Dam-2.1
4Kootenai River below Libby Dam0.3
4Kootenai River below Libby Dam0.3
5Fisher River1
5Fisher River1
6Yaak River-1
6Yaak River-1
7North FK. Flathead River-2.2
7North FK. Flathead River-2.2
8Middle FK. Flathead River-1.5
8Middle FK. Flathead River-1.5
9South FK. Flathead River-0.2
9South FK. Flathead River-0.2
10Flathead at Columbia Falls-1.3
10Flathead at Columbia Falls-1.3
11Stillwater/Whitefish Rivers-9.9
11Stillwater/Whitefish Rivers-9.9
12Swan River-0.5
12Swan River-0.5
13Flathead River at Polson-1
13Flathead River at Polson-1
14Mission Valley1.2
14Mission Valley1.2
15Little Bitterroot River-0.8
15Little Bitterroot River-0.8
16Clark above Missoula1.1
16Clark above Missoula1.1
17Blackfoot River0.5
17Blackfoot River0.5
18Clark Fork above Missoula0.9
18Clark Fork above Missoula0.9
19Bitterroot River0.4
19Bitterroot River0.4
20Clark Fork River below Bitterroot River0.7
20Clark Fork River below Bitterroot River0.7
21Clark Fork River below Flathead River-0.4
21Clark Fork River below Flathead River-0.4
22Beaverhead River-0.2
22Beaverhead River-0.2
23Ruby River-0.5
23Ruby River-0.5
24Big Hole River1.3
24Big Hole River1.3
25Boulder River (Jefferson)0.9
25Boulder River (Jefferson)0.9
26Jefferson River1.7
26Jefferson River1.7
27Madison River-0.4
27Madison River-0.4
28Gallatin River0.9
28Gallatin River0.9
29Missouri River above Canyon Ferry0.2
29Missouri River above Canyon Ferry0.2
30Missouri River below Canyon Ferry0.3
30Missouri River below Canyon Ferry0.3
31Smith River0.5
31Smith River0.5
32Sun River-0.4
32Sun River-0.4
33Teton River0.3
33Teton River0.3
34Birch/Dupuyer-1.3
34Birch/Dupuyer-1.3
35Marias Below Tiber Reservoir-1.2
35Marias Below Tiber Reservoir-1.2
36Musselshell River1.1
36Musselshell River1.1
37Missouri River above Fort Peck0.6
37Missouri River above Fort Peck0.6
38Missouri River below Fort Peck-2.4
38Missouri River below Fort Peck-2.4
39Milk River0.5
39Milk River0.5
40Dearborn-1
40Dearborn-1
41Yellowstone River above Livingston0.8
41Yellowstone River above Livingston0.8
42Shields River0.2
42Shields River0.2
43Boulder River (Yellowstone)2.2
43Boulder River (Yellowstone)2.2
44Stillwater River0.3
44Stillwater River0.3
45Rock/Red Lodge Creeks0.1
45Rock/Red Lodge Creeks0.1
46Clarks Fork River0.6
46Clarks Fork River0.6
47Yellowstone River above Bighorn River0.8
47Yellowstone River above Bighorn River0.8
48Bighorn River below Bighorn Lake0.9
48Bighorn River below Bighorn Lake0.9
49Little Bighorn River1.8
49Little Bighorn River1.8
50Yellowstone River below Bighorn River0.9
50Yellowstone River below Bighorn River0.9
51Tongue River3.1
51Tongue River3.1
52Powder River2.4
52Powder River2.4
53Upper Judith River1.1
53Upper Judith River1.1
54Saint Mary River-2.4
54Saint Mary River-2.4