May 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 Reservoir0.3
1Marias Above Tiber Reservoir0.3
2Tobacco1.6
2Tobacco1.6
3Kootenai to Libby Dam0.6
3Kootenai to Libby Dam0.6
4Kootenai River below Libby Dam1.7
4Kootenai River below Libby Dam1.7
5Fisher River2.2
5Fisher River2.2
6Yaak River1
6Yaak River1
7North FK. Flathead River0.4
7North FK. Flathead River0.4
8Middle FK. Flathead River0.1
8Middle FK. Flathead River0.1
9South FK. Flathead River-0.9
9South FK. Flathead River-0.9
10Flathead at Columbia Falls0
10Flathead at Columbia Falls0
11Stillwater/Whitefish Rivers-9.9
11Stillwater/Whitefish Rivers-9.9
12Swan River-1.1
12Swan River-1.1
13Flathead River at Polson1
13Flathead River at Polson1
14Mission Valley-2.5
14Mission Valley-2.5
15Little Bitterroot River3.2
15Little Bitterroot River3.2
16Clark above Missoula1.6
16Clark above Missoula1.6
17Blackfoot River0
17Blackfoot River0
18Clark Fork above Missoula1.6
18Clark Fork above Missoula1.6
19Bitterroot River1.8
19Bitterroot River1.8
20Clark Fork River below Bitterroot River1.7
20Clark Fork River below Bitterroot River1.7
21Clark Fork River below Flathead River1.2
21Clark Fork River below Flathead River1.2
22Beaverhead River-1
22Beaverhead River-1
23Ruby River0.7
23Ruby River0.7
24Big Hole River0.8
24Big Hole River0.8
25Boulder River (Jefferson)-0.1
25Boulder River (Jefferson)-0.1
26Jefferson River0.7
26Jefferson River0.7
27Madison River2.4
27Madison River2.4
28Gallatin River1.2
28Gallatin River1.2
29Missouri River above Canyon Ferry1.2
29Missouri River above Canyon Ferry1.2
30Missouri River below Canyon Ferry0.4
30Missouri River below Canyon Ferry0.4
31Smith River-0.2
31Smith River-0.2
32Sun River-0.4
32Sun River-0.4
33Teton River0.5
33Teton River0.5
34Birch/Dupuyer-2.8
34Birch/Dupuyer-2.8
35Marias Below Tiber Reservoir-0.6
35Marias Below Tiber Reservoir-0.6
36Musselshell River-1.3
36Musselshell River-1.3
37Missouri River above Fort Peck-0.5
37Missouri River above Fort Peck-0.5
38Missouri River below Fort Peck-3
38Missouri River below Fort Peck-3
39Milk River-3.1
39Milk River-3.1
40Dearborn0.9
40Dearborn0.9
41Yellowstone River above Livingston1.8
41Yellowstone River above Livingston1.8
42Shields River0
42Shields River0
43Boulder River (Yellowstone)0.5
43Boulder River (Yellowstone)0.5
44Stillwater River0.3
44Stillwater River0.3
45Rock/Red Lodge Creeks-2.6
45Rock/Red Lodge Creeks-2.6
46Clarks Fork River2.1
46Clarks Fork River2.1
47Yellowstone River above Bighorn River1.5
47Yellowstone River above Bighorn River1.5
48Bighorn River below Bighorn Lake-0.2
48Bighorn River below Bighorn Lake-0.2
49Little Bighorn River0.9
49Little Bighorn River0.9
50Yellowstone River below Bighorn River0.7
50Yellowstone River below Bighorn River0.7
51Tongue River1.7
51Tongue River1.7
52Powder River1.3
52Powder River1.3
53Upper Judith River-2.5
53Upper Judith River-2.5
54Saint Mary River0.7
54Saint Mary River0.7