July 2011
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 Reservoir3.7
1Marias Above Tiber Reservoir3.7
2Tobacco4
2Tobacco4
3Kootenai to Libby Dam3
3Kootenai to Libby Dam3
4Kootenai River below Libby Dam2.2
4Kootenai River below Libby Dam2.2
5Fisher River3.9
5Fisher River3.9
6Yaak River3.9
6Yaak River3.9
7North FK. Flathead River3.8
7North FK. Flathead River3.8
8Middle FK. Flathead River4
8Middle FK. Flathead River4
9South FK. Flathead River4
9South FK. Flathead River4
10Flathead at Columbia Falls3.9
10Flathead at Columbia Falls3.9
12Swan River3.9
12Swan River3.9
13Flathead River at Polson4
13Flathead River at Polson4
14Mission Valley0
14Mission Valley0
15Little Bitterroot River0
15Little Bitterroot River0
16Clark above Missoula3.9
16Clark above Missoula3.9
17Blackfoot River4
17Blackfoot River4
18Clark Fork above Missoula4
18Clark Fork above Missoula4
19Bitterroot River3
19Bitterroot River3
20Clark Fork River below Bitterroot River3.7
20Clark Fork River below Bitterroot River3.7
21Clark Fork River below Flathead River3.9
21Clark Fork River below Flathead River3.9
22Beaverhead River3
22Beaverhead River3
23Ruby River3.3
23Ruby River3.3
24Big Hole River3.8
24Big Hole River3.8
25Boulder River (Jefferson)3.9
25Boulder River (Jefferson)3.9
26Jefferson River3.8
26Jefferson River3.8
27Madison River3.4
27Madison River3.4
28Gallatin River3.7
28Gallatin River3.7
29Missouri River above Canyon Ferry3.8
29Missouri River above Canyon Ferry3.8
30Missouri River below Canyon Ferry3.9
30Missouri River below Canyon Ferry3.9
31Smith River4
31Smith River4
32Sun River3.6
32Sun River3.6
33Teton River3.6
33Teton River3.6
34Birch/Dupuyer3.6
34Birch/Dupuyer3.6
35Marias Below Tiber Reservoir3.9
35Marias Below Tiber Reservoir3.9
36Musselshell River3.8
36Musselshell River3.8
37Missouri River above Fort Peck3.8
37Missouri River above Fort Peck3.8
38Missouri River below Fort Peck3.7
38Missouri River below Fort Peck3.7
39Milk River3.8
39Milk River3.8
40Dearborn3.2
40Dearborn3.2
41Yellowstone River above Livingston3.7
41Yellowstone River above Livingston3.7
42Shields River3.9
42Shields River3.9
43Boulder River (Yellowstone)3.8
43Boulder River (Yellowstone)3.8
44Stillwater River3.5
44Stillwater River3.5
45Rock/Red Lodge Creeks3.8
45Rock/Red Lodge Creeks3.8
46Clarks Fork River3.7
46Clarks Fork River3.7
47Yellowstone River above Bighorn River3.7
47Yellowstone River above Bighorn River3.7
48Bighorn River below Bighorn Lake4
48Bighorn River below Bighorn Lake4
49Little Bighorn River4
49Little Bighorn River4
50Yellowstone River below Bighorn River3.8
50Yellowstone River below Bighorn River3.8
51Tongue River4
51Tongue River4
52Powder River4
52Powder River4
54Saint Mary River3.2
54Saint Mary River3.2