April 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 Reservoir0.6
1Marias River above Tiber Reservoir0.6
2Tobacco River0.4
2Tobacco River0.4
3Kootenai Ft. Steele to Libby Dam1
3Kootenai Ft. Steele to Libby Dam1
4Kootenai River below Libby Dam3.8
4Kootenai River below Libby Dam3.8
5Fisher River1.6
5Fisher River1.6
6Yaak River0.8
6Yaak River0.8
7North Fk. Flathead River1.7
7North Fk. Flathead River1.7
8Middle Fk. Flathead River2
8Middle Fk. Flathead River2
9South Fk. Flathead River4
9South Fk. Flathead River4
10Flathead River at Columbia Falls2.9
10Flathead River at Columbia Falls2.9
11Stillwater/Whitefish Rivers 
11Stillwater/Whitefish Rivers 
12Swan River3.3
12Swan River3.3
13Flathead River at Polson2.1
13Flathead River at Polson2.1
14Mission Valley0.2
14Mission Valley0.2
15Little Bitterroot River3.2
15Little Bitterroot River3.2
16Clark Fork River above Milltown3.3
16Clark Fork River above Milltown3.3
17Blackfoot River2.6
17Blackfoot River2.6
18Clark Fork River above Missoula3
18Clark Fork River above Missoula3
19Bitterroot River2.6
19Bitterroot River2.6
20Clark Fork River below Bitterroot River2.9
20Clark Fork River below Bitterroot River2.9
21Clark Fork River below Flathead River2.4
21Clark Fork River below Flathead River2.4
22Beaverhead River-1
22Beaverhead River-1
23Ruby River0
23Ruby River0
24Big Hole River2.6
24Big Hole River2.6
25Boulder River (Jefferson)2.9
25Boulder River (Jefferson)2.9
26Jefferson River2.2
26Jefferson River2.2
27Madison River0.3
27Madison River0.3
28Gallatin River2.1
28Gallatin River2.1
29Missouri River above Canyon Ferry1.9
29Missouri River above Canyon Ferry1.9
30Missouri River below Canyon Ferry1.4
30Missouri River below Canyon Ferry1.4
31Smith River3
31Smith River3
32Sun River1.6
32Sun River1.6
33Teton River1.9
33Teton River1.9
34Birch/Dupuyer Creeks-0.8
34Birch/Dupuyer Creeks-0.8
35Marias River below Tiber Reservoir2.3
35Marias River below Tiber Reservoir2.3
36Musselshell River3
36Musselshell River3
37Missouri River above Fort Peck1.4
37Missouri River above Fort Peck1.4
38Missouri River below Fort Peck0.1
38Missouri River below Fort Peck0.1
39Milk River1.2
39Milk River1.2
40Dearborn River near Craig1.7
40Dearborn River near Craig1.7
41Yellowstone River above Livingston3.2
41Yellowstone River above Livingston3.2
42Shields River3.3
42Shields River3.3
43Boulder River (Yellowstone)3.5
43Boulder River (Yellowstone)3.5
44Stillwater River3
44Stillwater River3
45Rock/Red Lodge Creeks3.2
45Rock/Red Lodge Creeks3.2
46Clarks Fork River3.3
46Clarks Fork River3.3
47Yellowstone River above Bighorn River3.2
47Yellowstone River above Bighorn River3.2
48Bighorn River below Bighorn Lake3.8
48Bighorn River below Bighorn Lake3.8
49Little Bighorn River2.1
49Little Bighorn River2.1
50Yellowstone River below Bighorn River3.5
50Yellowstone River below Bighorn River3.5
51Tongue River3
51Tongue River3
52Powder River3.3
52Powder River3.3
53Upper Judith Basin2.4
53Upper Judith Basin2.4
54St. Mary River2
54St. Mary River2