May 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-9.9
1Marias Above Tiber Reservoir-9.9
2Tobacco-0.9
2Tobacco-0.9
3Kootenai to Libby Dam-1
3Kootenai to Libby Dam-1
4Kootenai River below Libby Dam-0.3
4Kootenai River below Libby Dam-0.3
5Fisher River1.4
5Fisher River1.4
6Yaak River-0.4
6Yaak River-0.4
7North FK. Flathead River-2.2
7North FK. Flathead River-2.2
8Middle FK. Flathead River-0.5
8Middle FK. Flathead River-0.5
9South FK. Flathead River2.4
9South FK. Flathead River2.4
10Flathead at Columbia Falls0.1
10Flathead at Columbia Falls0.1
11Stillwater/Whitefish Rivers-9.9
11Stillwater/Whitefish Rivers-9.9
12Swan River-0.6
12Swan River-0.6
13Flathead River at Polson0.9
13Flathead River at Polson0.9
14Mission Valley-9.9
14Mission Valley-9.9
15Little Bitterroot River-9.9
15Little Bitterroot River-9.9
16Clark above Missoula2.1
16Clark above Missoula2.1
17Blackfoot River2.3
17Blackfoot River2.3
18Clark Fork above Missoula2.1
18Clark Fork above Missoula2.1
19Bitterroot River1
19Bitterroot River1
20Clark Fork River below Bitterroot River1.8
20Clark Fork River below Bitterroot River1.8
21Clark Fork River below Flathead River1.2
21Clark Fork River below Flathead River1.2
22Beaverhead River0.5
22Beaverhead River0.5
23Ruby River1.1
23Ruby River1.1
24Big Hole River2.2
24Big Hole River2.2
25Boulder River (Jefferson)2.3
25Boulder River (Jefferson)2.3
26Jefferson River1.7
26Jefferson River1.7
27Madison River0.7
27Madison River0.7
28Gallatin River2.1
28Gallatin River2.1
29Missouri River above Canyon Ferry1.4
29Missouri River above Canyon Ferry1.4
30Missouri River below Canyon Ferry1.1
30Missouri River below Canyon Ferry1.1
31Smith River0.7
31Smith River0.7
32Sun River1.1
32Sun River1.1
33Teton River0.8
33Teton River0.8
34Birch/Dupuyer-0.6
34Birch/Dupuyer-0.6
35Marias Below Tiber Reservoir-9.9
35Marias Below Tiber Reservoir-9.9
36Musselshell River1.3
36Musselshell River1.3
37Missouri River above Fort Peck-9.9
37Missouri River above Fort Peck-9.9
38Missouri River below Fort Peck-1.7
38Missouri River below Fort Peck-1.7
39Milk River-0.1
39Milk River-0.1
40Dearborn0.2
40Dearborn0.2
41Yellowstone River above Livingston1.7
41Yellowstone River above Livingston1.7
42Shields River0.2
42Shields River0.2
43Boulder River (Yellowstone)3.3
43Boulder River (Yellowstone)3.3
44Stillwater River0.7
44Stillwater River0.7
45Rock/Red Lodge Creeks1.5
45Rock/Red Lodge Creeks1.5
46Clarks Fork River1.4
46Clarks Fork River1.4
47Yellowstone River above Bighorn River1.6
47Yellowstone River above Bighorn River1.6
48Bighorn River below Bighorn Lake2.9
48Bighorn River below Bighorn Lake2.9
49Little Bighorn River1.2
49Little Bighorn River1.2
50Yellowstone River below Bighorn River2.2
50Yellowstone River below Bighorn River2.2
51Tongue River2.6
51Tongue River2.6
52Powder River1.9
52Powder River1.9
53Upper Judith River1.8
53Upper Judith River1.8
54Saint Mary River-1.1
54Saint Mary River-1.1