September 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 Reservoir-1.2
1Marias Above Tiber Reservoir-1.2
2Tobacco-1.2
2Tobacco-1.2
3Kootenai to Libby Dam-1
3Kootenai to Libby Dam-1
4Kootenai River below Libby Dam-1.8
4Kootenai River below Libby Dam-1.8
5Fisher River0.2
5Fisher River0.2
6Yaak River-1.5
6Yaak River-1.5
7North FK. Flathead River-0.6
7North FK. Flathead River-0.6
8Middle FK. Flathead River0
8Middle FK. Flathead River0
9South FK. Flathead River-0.9
9South FK. Flathead River-0.9
10Flathead at Columbia Falls-0.8
10Flathead at Columbia Falls-0.8
12Swan River0.4
12Swan River0.4
13Flathead River at Polson0.2
13Flathead River at Polson0.2
14Mission Valley-0.6
14Mission Valley-0.6
15Little Bitterroot River-1.6
15Little Bitterroot River-1.6
16Clark above Missoula1.2
16Clark above Missoula1.2
17Blackfoot River-0.2
17Blackfoot River-0.2
18Clark Fork above Missoula0.4
18Clark Fork above Missoula0.4
19Bitterroot River1
19Bitterroot River1
20Clark Fork River below Bitterroot River0.6
20Clark Fork River below Bitterroot River0.6
21Clark Fork River below Flathead River0.3
21Clark Fork River below Flathead River0.3
22Beaverhead River-1.6
22Beaverhead River-1.6
23Ruby River2.4
23Ruby River2.4
24Big Hole River-0.7
24Big Hole River-0.7
25Boulder River (Jefferson)-0.6
25Boulder River (Jefferson)-0.6
26Jefferson River-0.3
26Jefferson River-0.3
27Madison River0.5
27Madison River0.5
28Gallatin River0.7
28Gallatin River0.7
29Missouri River above Canyon Ferry-1
29Missouri River above Canyon Ferry-1
30Missouri River below Canyon Ferry0.6
30Missouri River below Canyon Ferry0.6
31Smith River-1.3
31Smith River-1.3
32Sun River0.7
32Sun River0.7
33Teton River-1.2
33Teton River-1.2
34Birch/Dupuyer0.4
34Birch/Dupuyer0.4
35Marias Below Tiber Reservoir1
35Marias Below Tiber Reservoir1
36Musselshell River-1
36Musselshell River-1
37Missouri River above Fort Peck1.1
37Missouri River above Fort Peck1.1
38Missouri River below Fort Peck-2.4
38Missouri River below Fort Peck-2.4
39Milk River1.1
39Milk River1.1
40Dearborn0
40Dearborn0
41Yellowstone River above Livingston1.6
41Yellowstone River above Livingston1.6
42Shields River-1.2
42Shields River-1.2
43Boulder River (Yellowstone)2.1
43Boulder River (Yellowstone)2.1
44Stillwater River-0.8
44Stillwater River-0.8
45Rock/Red Lodge Creeks2.2
45Rock/Red Lodge Creeks2.2
46Clarks Fork River1
46Clarks Fork River1
47Yellowstone River above Bighorn River1.2
47Yellowstone River above Bighorn River1.2
48Bighorn River below Bighorn Lake1.9
48Bighorn River below Bighorn Lake1.9
49Little Bighorn River0.6
49Little Bighorn River0.6
50Yellowstone River below Bighorn River1.5
50Yellowstone River below Bighorn River1.5
51Tongue River3.9
51Tongue River3.9
52Powder River0.3
52Powder River0.3
53Upper Judith River-3.2
53Upper Judith River-3.2
54Saint Mary River0.7
54Saint Mary River0.7