September 2014
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 River above Tiber Reservoir0.7
1Marias River above Tiber Reservoir0.7
2Tobacco River0.2
2Tobacco River0.2
3Kootenai Ft. Steele to Libby Dam-1.1
3Kootenai Ft. Steele to Libby Dam-1.1
4Kootenai River below Libby Dam0.3
4Kootenai River below Libby Dam0.3
5Fisher River1.2
5Fisher River1.2
6Yaak River-0.6
6Yaak River-0.6
7North Fk. Flathead River0.5
7North Fk. Flathead River0.5
8Middle Fk. Flathead River1.2
8Middle Fk. Flathead River1.2
9South Fk. Flathead River1.6
9South Fk. Flathead River1.6
10Flathead River at Columbia Falls1.5
10Flathead River at Columbia Falls1.5
11Stillwater/Whitefish Rivers 
11Stillwater/Whitefish Rivers 
12Swan River1.5
12Swan River1.5
13Flathead River at Polson0.9
13Flathead River at Polson0.9
14Mission Valley2.2
14Mission Valley2.2
15Little Bitterroot River3.9
15Little Bitterroot River3.9
16Clark Fork River above Milltown1.8
16Clark Fork River above Milltown1.8
17Blackfoot River1.2
17Blackfoot River1.2
18Clark Fork River above Missoula1.8
18Clark Fork River above Missoula1.8
19Bitterroot River1.7
19Bitterroot River1.7
20Clark Fork River below Bitterroot River1.8
20Clark Fork River below Bitterroot River1.8
21Clark Fork River below Flathead River1.2
21Clark Fork River below Flathead River1.2
22Beaverhead River-1.3
22Beaverhead River-1.3
23Ruby River1.2
23Ruby River1.2
24Big Hole River1.7
24Big Hole River1.7
25Boulder River (Jefferson)2.5
25Boulder River (Jefferson)2.5
26Jefferson River0.4
26Jefferson River0.4
27Madison River0.4
27Madison River0.4
28Gallatin River0.1
28Gallatin River0.1
29Missouri River above Canyon Ferry0.1
29Missouri River above Canyon Ferry0.1
30Missouri River below Canyon Ferry1.4
30Missouri River below Canyon Ferry1.4
31Smith River2.8
31Smith River2.8
32Sun River1
32Sun River1
33Teton River0.1
33Teton River0.1
34Birch/Dupuyer Creeks0.3
34Birch/Dupuyer Creeks0.3
35Marias River below Tiber Reservoir2.9
35Marias River below Tiber Reservoir2.9
36Musselshell River2.8
36Musselshell River2.8
37Missouri River above Fort Peck1.8
37Missouri River above Fort Peck1.8
38Missouri River below Fort Peck0.1
38Missouri River below Fort Peck0.1
39Milk River 
39Milk River 
40Dearborn River near Craig2.8
40Dearborn River near Craig2.8
41Yellowstone River above Livingston2.5
41Yellowstone River above Livingston2.5
42Shields River2.2
42Shields River2.2
43Boulder River (Yellowstone)3
43Boulder River (Yellowstone)3
44Stillwater River1.7
44Stillwater River1.7
45Rock/Red Lodge Creeks2.8
45Rock/Red Lodge Creeks2.8
46Clarks Fork River2.7
46Clarks Fork River2.7
47Yellowstone River above Bighorn River2.4
47Yellowstone River above Bighorn River2.4
48Bighorn River below Bighorn Lake3
48Bighorn River below Bighorn Lake3
49Little Bighorn River1.8
49Little Bighorn River1.8
50Yellowstone River below Bighorn River2.7
50Yellowstone River below Bighorn River2.7
51Tongue River3.9
51Tongue River3.9
52Powder River1.6
52Powder River1.6
53Upper Judith Basin3.6
53Upper Judith Basin3.6
54St. Mary River1.1
54St. Mary River1.1