March 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 Reservoir0.6
1Marias Above Tiber Reservoir0.6
2Tobacco1.7
2Tobacco1.7
3Kootenai to Libby Dam1.5
3Kootenai to Libby Dam1.5
4Kootenai River below Libby Dam2.9
4Kootenai River below Libby Dam2.9
5Fisher River1.5
5Fisher River1.5
6Yaak River0.8
6Yaak River0.8
7North FK. Flathead River2.3
7North FK. Flathead River2.3
8Middle FK. Flathead River2.1
8Middle FK. Flathead River2.1
9South FK. Flathead River3.7
9South FK. Flathead River3.7
10Flathead at Columbia Falls2.7
10Flathead at Columbia Falls2.7
12Swan River3.4
12Swan River3.4
13Flathead River at Polson2.4
13Flathead River at Polson2.4
14Mission Valley0
14Mission Valley0
15Little Bitterroot River1.3
15Little Bitterroot River1.3
16Clark above Missoula1.5
16Clark above Missoula1.5
17Blackfoot River2.4
17Blackfoot River2.4
18Clark Fork above Missoula1.9
18Clark Fork above Missoula1.9
19Bitterroot River1.4
19Bitterroot River1.4
20Clark Fork River below Bitterroot River1.8
20Clark Fork River below Bitterroot River1.8
21Clark Fork River below Flathead River2.2
21Clark Fork River below Flathead River2.2
22Beaverhead River0.8
22Beaverhead River0.8
23Ruby River1.1
23Ruby River1.1
24Big Hole River1.2
24Big Hole River1.2
25Boulder River (Jefferson)0.2
25Boulder River (Jefferson)0.2
26Jefferson River1.8
26Jefferson River1.8
27Madison River0.3
27Madison River0.3
28Gallatin River1.1
28Gallatin River1.1
29Missouri River above Canyon Ferry0.5
29Missouri River above Canyon Ferry0.5
30Missouri River below Canyon Ferry0.1
30Missouri River below Canyon Ferry0.1
31Smith River2.6
31Smith River2.6
32Sun River1.4
32Sun River1.4
33Teton River1.7
33Teton River1.7
34Birch/Dupuyer1.3
34Birch/Dupuyer1.3
35Marias Below Tiber Reservoir2.7
35Marias Below Tiber Reservoir2.7
36Musselshell River2.4
36Musselshell River2.4
37Missouri River above Fort Peck0.9
37Missouri River above Fort Peck0.9
38Missouri River below Fort Peck1.1
38Missouri River below Fort Peck1.1
39Milk River3.1
39Milk River3.1
40Dearborn2
40Dearborn2
41Yellowstone River above Livingston1.7
41Yellowstone River above Livingston1.7
42Shields River2.1
42Shields River2.1
43Boulder River (Yellowstone)2.4
43Boulder River (Yellowstone)2.4
44Stillwater River-0.1
44Stillwater River-0.1
45Rock/Red Lodge Creeks-0.9
45Rock/Red Lodge Creeks-0.9
46Clarks Fork River1.5
46Clarks Fork River1.5
47Yellowstone River above Bighorn River1.5
47Yellowstone River above Bighorn River1.5
48Bighorn River below Bighorn Lake0.4
48Bighorn River below Bighorn Lake0.4
49Little Bighorn River1.2
49Little Bighorn River1.2
50Yellowstone River below Bighorn River1
50Yellowstone River below Bighorn River1
51Tongue River1
51Tongue River1
52Powder River1.1
52Powder River1.1
53Upper Judith River3.5
53Upper Judith River3.5
54Saint Mary River2.5
54Saint Mary River2.5