June 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 Reservoir1
1Marias River above Tiber Reservoir1
2Tobacco River1.1
2Tobacco River1.1
3Kootenai Ft. Steele to Libby Dam1.8
3Kootenai Ft. Steele to Libby Dam1.8
4Kootenai River below Libby Dam1.4
4Kootenai River below Libby Dam1.4
5Fisher River1.4
5Fisher River1.4
6Yaak River0.1
6Yaak River0.1
7North Fk. Flathead River2.4
7North Fk. Flathead River2.4
8Middle Fk. Flathead River2.4
8Middle Fk. Flathead River2.4
9South Fk. Flathead River3.1
9South Fk. Flathead River3.1
10Flathead River at Columbia Falls2
10Flathead River at Columbia Falls2
11Stillwater/Whitefish Rivers 
11Stillwater/Whitefish Rivers 
12Swan River2.5
12Swan River2.5
13Flathead River at Polson2.9
13Flathead River at Polson2.9
14Mission Valley-0.6
14Mission Valley-0.6
15Little Bitterroot River2.1
15Little Bitterroot River2.1
16Clark Fork River above Milltown1.1
16Clark Fork River above Milltown1.1
17Blackfoot River2.5
17Blackfoot River2.5
18Clark Fork River above Missoula1.7
18Clark Fork River above Missoula1.7
19Bitterroot River2.4
19Bitterroot River2.4
20Clark Fork River below Bitterroot River1.9
20Clark Fork River below Bitterroot River1.9
21Clark Fork River below Flathead River2.5
21Clark Fork River below Flathead River2.5
22Beaverhead River-1.6
22Beaverhead River-1.6
23Ruby River-0.7
23Ruby River-0.7
24Big Hole River2.3
24Big Hole River2.3
25Boulder River (Jefferson)2.8
25Boulder River (Jefferson)2.8
26Jefferson River1.8
26Jefferson River1.8
27Madison River0.3
27Madison River0.3
28Gallatin River2.2
28Gallatin River2.2
29Missouri River above Canyon Ferry0.9
29Missouri River above Canyon Ferry0.9
30Missouri River below Canyon Ferry1.1
30Missouri River below Canyon Ferry1.1
31Smith River2.9
31Smith River2.9
32Sun River1.4
32Sun River1.4
33Teton River1.2
33Teton River1.2
34Birch/Dupuyer Creeks-0.2
34Birch/Dupuyer Creeks-0.2
35Marias River below Tiber Reservoir1.6
35Marias River below Tiber Reservoir1.6
36Musselshell River2.1
36Musselshell River2.1
37Missouri River above Fort Peck0.7
37Missouri River above Fort Peck0.7
38Missouri River below Fort Peck0.5
38Missouri River below Fort Peck0.5
39Milk River 
39Milk River 
40Dearborn River near Craig1.3
40Dearborn River near Craig1.3
41Yellowstone River above Livingston3.2
41Yellowstone River above Livingston3.2
42Shields River2.1
42Shields River2.1
43Boulder River (Yellowstone)3.5
43Boulder River (Yellowstone)3.5
44Stillwater River3
44Stillwater River3
45Rock/Red Lodge Creeks3.4
45Rock/Red Lodge Creeks3.4
46Clarks Fork River3.8
46Clarks Fork River3.8
47Yellowstone River above Bighorn River3.2
47Yellowstone River above Bighorn River3.2
48Bighorn River below Bighorn Lake2.4
48Bighorn River below Bighorn Lake2.4
49Little Bighorn River2.5
49Little Bighorn River2.5
50Yellowstone River below Bighorn River2.9
50Yellowstone River below Bighorn River2.9
51Tongue River3.1
51Tongue River3.1
52Powder River2.2
52Powder River2.2
53Upper Judith Basin1
53Upper Judith Basin1
54St. Mary River1.8
54St. Mary River1.8