June 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 Reservoir3.4
1Marias Above Tiber Reservoir3.4
2Tobacco3.4
2Tobacco3.4
3Kootenai to Libby Dam2.4
3Kootenai to Libby Dam2.4
4Kootenai River below Libby Dam0
4Kootenai River below Libby Dam0
5Fisher River3.8
5Fisher River3.8
6Yaak River3.2
6Yaak River3.2
7North FK. Flathead River3.8
7North FK. Flathead River3.8
8Middle FK. Flathead River3.8
8Middle FK. Flathead River3.8
9South FK. Flathead River3.8
9South FK. Flathead River3.8
10Flathead at Columbia Falls3.2
10Flathead at Columbia Falls3.2
12Swan River3.9
12Swan River3.9
13Flathead River at Polson3.8
13Flathead River at Polson3.8
14Mission Valley0
14Mission Valley0
15Little Bitterroot River0
15Little Bitterroot River0
16Clark above Missoula3.5
16Clark above Missoula3.5
17Blackfoot River4
17Blackfoot River4
18Clark Fork above Missoula3.6
18Clark Fork above Missoula3.6
19Bitterroot River2.5
19Bitterroot River2.5
20Clark Fork River below Bitterroot River3.2
20Clark Fork River below Bitterroot River3.2
21Clark Fork River below Flathead River3.6
21Clark Fork River below Flathead River3.6
22Beaverhead River2.3
22Beaverhead River2.3
23Ruby River2.4
23Ruby River2.4
24Big Hole River3.7
24Big Hole River3.7
25Boulder River (Jefferson)3
25Boulder River (Jefferson)3
26Jefferson River3
26Jefferson River3
27Madison River2.8
27Madison River2.8
28Gallatin River3.4
28Gallatin River3.4
29Missouri River above Canyon Ferry3.3
29Missouri River above Canyon Ferry3.3
30Missouri River below Canyon Ferry3.1
30Missouri River below Canyon Ferry3.1
32Sun River3.2
32Sun River3.2
33Teton River2.3
33Teton River2.3
34Birch/Dupuyer3.3
34Birch/Dupuyer3.3
35Marias Below Tiber Reservoir3.9
35Marias Below Tiber Reservoir3.9
36Musselshell River3.8
36Musselshell River3.8
37Missouri River above Fort Peck2.3
37Missouri River above Fort Peck2.3
38Missouri River below Fort Peck3.9
38Missouri River below Fort Peck3.9
39Milk River3.9
39Milk River3.9
40Dearborn2.8
40Dearborn2.8
41Yellowstone River above Livingston3.7
41Yellowstone River above Livingston3.7
42Shields River3.8
42Shields River3.8
43Boulder River (Yellowstone)3.6
43Boulder River (Yellowstone)3.6
44Stillwater River3.8
44Stillwater River3.8
45Rock/Red Lodge Creeks3.8
45Rock/Red Lodge Creeks3.8
46Clarks Fork River3.9
46Clarks Fork River3.9
47Yellowstone River above Bighorn River3.7
47Yellowstone River above Bighorn River3.7
48Bighorn River below Bighorn Lake4
48Bighorn River below Bighorn Lake4
49Little Bighorn River3.8
49Little Bighorn River3.8
50Yellowstone River below Bighorn River3.8
50Yellowstone River below Bighorn River3.8
51Tongue River3.9
51Tongue River3.9
52Powder River4
52Powder River4
54Saint Mary River3.3
54Saint Mary River3.3