July 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-1
2Tobacco-1
3Kootenai to Libby Dam-2.5
3Kootenai to Libby Dam-2.5
4Kootenai River below Libby Dam-2.5
4Kootenai River below Libby Dam-2.5
5Fisher River0.7
5Fisher River0.7
6Yaak River-0.3
6Yaak River-0.3
7North FK. Flathead River-2.3
7North FK. Flathead River-2.3
8Middle FK. Flathead River-0.2
8Middle FK. Flathead River-0.2
9South FK. Flathead River0.3
9South FK. Flathead River0.3
10Flathead at Columbia Falls-0.6
10Flathead at Columbia Falls-0.6
12Swan River-1.1
12Swan River-1.1
13Flathead River at Polson-0.9
13Flathead River at Polson-0.9
14Mission Valley-3.5
14Mission Valley-3.5
15Little Bitterroot River-0.1
15Little Bitterroot River-0.1
16Clark above Missoula2.3
16Clark above Missoula2.3
17Blackfoot River1.5
17Blackfoot River1.5
18Clark Fork above Missoula1.9
18Clark Fork above Missoula1.9
19Bitterroot River1.2
19Bitterroot River1.2
20Clark Fork River below Bitterroot River1.7
20Clark Fork River below Bitterroot River1.7
21Clark Fork River below Flathead River0
21Clark Fork River below Flathead River0
22Beaverhead River1.3
22Beaverhead River1.3
23Ruby River-0.7
23Ruby River-0.7
24Big Hole River1.4
24Big Hole River1.4
25Boulder River (Jefferson)2
25Boulder River (Jefferson)2
26Jefferson River1.8
26Jefferson River1.8
27Madison River0.4
27Madison River0.4
28Gallatin River1.5
28Gallatin River1.5
29Missouri River above Canyon Ferry0.9
29Missouri River above Canyon Ferry0.9
30Missouri River below Canyon Ferry0.7
30Missouri River below Canyon Ferry0.7
31Smith River0.8
31Smith River0.8
32Sun River-0.2
32Sun River-0.2
33Teton River0.3
33Teton River0.3
34Birch/Dupuyer-0.1
34Birch/Dupuyer-0.1
35Marias Below Tiber Reservoir-9.9
35Marias Below Tiber Reservoir-9.9
36Musselshell River1.2
36Musselshell River1.2
37Missouri River above Fort Peck-9.9
37Missouri River above Fort Peck-9.9
38Missouri River below Fort Peck-1.5
38Missouri River below Fort Peck-1.5
39Milk River0.4
39Milk River0.4
40Dearborn0.5
40Dearborn0.5
41Yellowstone River above Livingston1.7
41Yellowstone River above Livingston1.7
42Shields River1.9
42Shields River1.9
43Boulder River (Yellowstone)2.7
43Boulder River (Yellowstone)2.7
44Stillwater River0.7
44Stillwater River0.7
45Rock/Red Lodge Creeks0.5
45Rock/Red Lodge Creeks0.5
46Clarks Fork River1.9
46Clarks Fork River1.9
47Yellowstone River above Bighorn River1.7
47Yellowstone River above Bighorn River1.7
48Bighorn River below Bighorn Lake1.5
48Bighorn River below Bighorn Lake1.5
49Little Bighorn River-1.2
49Little Bighorn River-1.2
50Yellowstone River below Bighorn River1.6
50Yellowstone River below Bighorn River1.6
51Tongue River0
51Tongue River0
52Powder River-0.1
52Powder River-0.1
53Upper Judith River3.2
53Upper Judith River3.2
54Saint Mary River-0.2
54Saint Mary River-0.2