May 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 Reservoir2.5
1Marias Above Tiber Reservoir2.5
2Tobacco2.3
2Tobacco2.3
3Kootenai to Libby Dam3.4
3Kootenai to Libby Dam3.4
4Kootenai River below Libby Dam2.7
4Kootenai River below Libby Dam2.7
5Fisher River1.5
5Fisher River1.5
6Yaak River1.6
6Yaak River1.6
7North FK. Flathead River3.3
7North FK. Flathead River3.3
8Middle FK. Flathead River3.8
8Middle FK. Flathead River3.8
9South FK. Flathead River3.9
9South FK. Flathead River3.9
10Flathead at Columbia Falls3.9
10Flathead at Columbia Falls3.9
12Swan River3.8
12Swan River3.8
13Flathead River at Polson3.5
13Flathead River at Polson3.5
14Mission Valley3.7
14Mission Valley3.7
15Little Bitterroot River3.8
15Little Bitterroot River3.8
16Clark above Missoula1.6
16Clark above Missoula1.6
17Blackfoot River2.5
17Blackfoot River2.5
18Clark Fork above Missoula2.5
18Clark Fork above Missoula2.5
19Bitterroot River2.2
19Bitterroot River2.2
20Clark Fork River below Bitterroot River2.4
20Clark Fork River below Bitterroot River2.4
21Clark Fork River below Flathead River3.1
21Clark Fork River below Flathead River3.1
22Beaverhead River0.4
22Beaverhead River0.4
23Ruby River1.3
23Ruby River1.3
24Big Hole River1.6
24Big Hole River1.6
25Boulder River (Jefferson)1.8
25Boulder River (Jefferson)1.8
26Jefferson River1.9
26Jefferson River1.9
27Madison River2.7
27Madison River2.7
28Gallatin River2.2
28Gallatin River2.2
29Missouri River above Canyon Ferry1.8
29Missouri River above Canyon Ferry1.8
30Missouri River below Canyon Ferry0.3
30Missouri River below Canyon Ferry0.3
32Sun River2.6
32Sun River2.6
33Teton River1.9
33Teton River1.9
34Birch/Dupuyer2.5
34Birch/Dupuyer2.5
35Marias Below Tiber Reservoir2.8
35Marias Below Tiber Reservoir2.8
36Musselshell River2.9
36Musselshell River2.9
37Missouri River above Fort Peck0.8
37Missouri River above Fort Peck0.8
38Missouri River below Fort Peck3.2
38Missouri River below Fort Peck3.2
39Milk River2.5
39Milk River2.5
40Dearborn2.4
40Dearborn2.4
41Yellowstone River above Livingston3.4
41Yellowstone River above Livingston3.4
42Shields River3
42Shields River3
43Boulder River (Yellowstone)3.4
43Boulder River (Yellowstone)3.4
44Stillwater River3.1
44Stillwater River3.1
45Rock/Red Lodge Creeks1.8
45Rock/Red Lodge Creeks1.8
46Clarks Fork River3.3
46Clarks Fork River3.3
47Yellowstone River above Bighorn River3.3
47Yellowstone River above Bighorn River3.3
48Bighorn River below Bighorn Lake3.3
48Bighorn River below Bighorn Lake3.3
49Little Bighorn River1.8
49Little Bighorn River1.8
50Yellowstone River below Bighorn River3.3
50Yellowstone River below Bighorn River3.3
51Tongue River2.6
51Tongue River2.6
52Powder River2.2
52Powder River2.2
54Saint Mary River3.1
54Saint Mary River3.1