March 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 Reservoir-1.2
1Marias River above Tiber Reservoir-1.2
2Tobacco River-0.8
2Tobacco River-0.8
3Kootenai Ft. Steele to Libby Dam-1
3Kootenai Ft. Steele to Libby Dam-1
4Kootenai River below Libby Dam2.3
4Kootenai River below Libby Dam2.3
5Fisher River0.2
5Fisher River0.2
6Yaak River-0.6
6Yaak River-0.6
7North Fk. Flathead River-1.2
7North Fk. Flathead River-1.2
8Middle Fk. Flathead River0.3
8Middle Fk. Flathead River0.3
9South Fk. Flathead River3.1
9South Fk. Flathead River3.1
10Flathead River at Columbia Falls0.8
10Flathead River at Columbia Falls0.8
11Stillwater/Whitefish Rivers 
11Stillwater/Whitefish Rivers 
12Swan River2.3
12Swan River2.3
13Flathead River at Polson0.3
13Flathead River at Polson0.3
14Mission Valley-1
14Mission Valley-1
15Little Bitterroot River0.6
15Little Bitterroot River0.6
16Clark Fork River above Milltown2.6
16Clark Fork River above Milltown2.6
17Blackfoot River2.4
17Blackfoot River2.4
18Clark Fork River above Missoula2.9
18Clark Fork River above Missoula2.9
19Bitterroot River2.4
19Bitterroot River2.4
20Clark Fork River below Bitterroot River2.8
20Clark Fork River below Bitterroot River2.8
21Clark Fork River below Flathead River1.2
21Clark Fork River below Flathead River1.2
22Beaverhead River-2.1
22Beaverhead River-2.1
23Ruby River-0.7
23Ruby River-0.7
24Big Hole River1.5
24Big Hole River1.5
25Boulder River (Jefferson)1.8
25Boulder River (Jefferson)1.8
26Jefferson River1.9
26Jefferson River1.9
27Madison River0
27Madison River0
28Gallatin River0.7
28Gallatin River0.7
29Missouri River above Canyon Ferry0.6
29Missouri River above Canyon Ferry0.6
30Missouri River below Canyon Ferry0.5
30Missouri River below Canyon Ferry0.5
31Smith River2.9
31Smith River2.9
32Sun River0.4
32Sun River0.4
33Teton River1.1
33Teton River1.1
34Birch/Dupuyer Creeks-2.1
34Birch/Dupuyer Creeks-2.1
35Marias River below Tiber Reservoir0.6
35Marias River below Tiber Reservoir0.6
36Musselshell River2.3
36Musselshell River2.3
37Missouri River above Fort Peck0.7
37Missouri River above Fort Peck0.7
38Missouri River below Fort Peck-0.9
38Missouri River below Fort Peck-0.9
39Milk River1.4
39Milk River1.4
40Dearborn River near Craig0.1
40Dearborn River near Craig0.1
41Yellowstone River above Livingston1.1
41Yellowstone River above Livingston1.1
42Shields River2.4
42Shields River2.4
43Boulder River (Yellowstone)2.2
43Boulder River (Yellowstone)2.2
44Stillwater River0.6
44Stillwater River0.6
45Rock/Red Lodge Creeks1.4
45Rock/Red Lodge Creeks1.4
46Clarks Fork River2.3
46Clarks Fork River2.3
47Yellowstone River above Bighorn River1.1
47Yellowstone River above Bighorn River1.1
48Bighorn River below Bighorn Lake3.2
48Bighorn River below Bighorn Lake3.2
49Little Bighorn River1.5
49Little Bighorn River1.5
50Yellowstone River below Bighorn River2
50Yellowstone River below Bighorn River2
51Tongue River2.5
51Tongue River2.5
52Powder River2.4
52Powder River2.4
53Upper Judith Basin3.4
53Upper Judith Basin3.4
54St. Mary River0.1
54St. Mary River0.1