October 2008
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 Reservoir0.6
1Marias Above Tiber Reservoir0.6
2Tobacco-2.6
2Tobacco-2.6
3Kootenai to Libby Dam-0.8
3Kootenai to Libby Dam-0.8
4Kootenai River below Libby Dam-1.3
4Kootenai River below Libby Dam-1.3
5Fisher River-0.7
5Fisher River-0.7
6Yaak River-0.9
6Yaak River-0.9
7North FK. Flathead River-1.7
7North FK. Flathead River-1.7
8Middle FK. Flathead River-0.2
8Middle FK. Flathead River-0.2
9South FK. Flathead River-1.9
9South FK. Flathead River-1.9
10Flathead at Columbia Falls-2
10Flathead at Columbia Falls-2
11Stillwater/Whitefish Rivers-9.9
11Stillwater/Whitefish Rivers-9.9
12Swan River1.4
12Swan River1.4
13Flathead River at Polson0.7
13Flathead River at Polson0.7
14Mission Valley1.8
14Mission Valley1.8
15Little Bitterroot River-2.5
15Little Bitterroot River-2.5
16Clark above Missoula2.1
16Clark above Missoula2.1
17Blackfoot River2.1
17Blackfoot River2.1
18Clark Fork above Missoula1.9
18Clark Fork above Missoula1.9
19Bitterroot River2.7
19Bitterroot River2.7
20Clark Fork River below Bitterroot River2.1
20Clark Fork River below Bitterroot River2.1
21Clark Fork River below Flathead River1.2
21Clark Fork River below Flathead River1.2
22Beaverhead River-1.4
22Beaverhead River-1.4
23Ruby River3.2
23Ruby River3.2
24Big Hole River0.7
24Big Hole River0.7
25Boulder River (Jefferson)-0.2
25Boulder River (Jefferson)-0.2
26Jefferson River-0.5
26Jefferson River-0.5
27Madison River-4
27Madison River-4
28Gallatin River-0.9
28Gallatin River-0.9
29Missouri River above Canyon Ferry-3.2
29Missouri River above Canyon Ferry-3.2
30Missouri River below Canyon Ferry0.8
30Missouri River below Canyon Ferry0.8
31Smith River1.4
31Smith River1.4
32Sun River0.7
32Sun River0.7
33Teton River-0.7
33Teton River-0.7
34Birch/Dupuyer-0.1
34Birch/Dupuyer-0.1
35Marias Below Tiber Reservoir2.3
35Marias Below Tiber Reservoir2.3
36Musselshell River-1.1
36Musselshell River-1.1
37Missouri River above Fort Peck1.6
37Missouri River above Fort Peck1.6
38Missouri River below Fort Peck-2.4
38Missouri River below Fort Peck-2.4
39Milk River2.5
39Milk River2.5
40Dearborn3.2
40Dearborn3.2
41Yellowstone River above Livingston0.5
41Yellowstone River above Livingston0.5
42Shields River-0.3
42Shields River-0.3
43Boulder River (Yellowstone)0.2
43Boulder River (Yellowstone)0.2
44Stillwater River-1.6
44Stillwater River-1.6
45Rock/Red Lodge Creeks3.4
45Rock/Red Lodge Creeks3.4
46Clarks Fork River1.2
46Clarks Fork River1.2
47Yellowstone River above Bighorn River0.2
47Yellowstone River above Bighorn River0.2
48Bighorn River below Bighorn Lake1.5
48Bighorn River below Bighorn Lake1.5
49Little Bighorn River1.5
49Little Bighorn River1.5
50Yellowstone River below Bighorn River0.8
50Yellowstone River below Bighorn River0.8
51Tongue River3.9
51Tongue River3.9
52Powder River0.9
52Powder River0.9
53Upper Judith River-3
53Upper Judith River-3
54Saint Mary River2.8
54Saint Mary River2.8