April 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 Reservoir1.2
1Marias Above Tiber Reservoir1.2
2Tobacco2.4
2Tobacco2.4
3Kootenai to Libby Dam1.9
3Kootenai to Libby Dam1.9
4Kootenai River below Libby Dam2.6
4Kootenai River below Libby Dam2.6
5Fisher River2.1
5Fisher River2.1
6Yaak River1.3
6Yaak River1.3
7North FK. Flathead River2.5
7North FK. Flathead River2.5
8Middle FK. Flathead River2.8
8Middle FK. Flathead River2.8
9South FK. Flathead River3.9
9South FK. Flathead River3.9
10Flathead at Columbia Falls3.5
10Flathead at Columbia Falls3.5
12Swan River3.8
12Swan River3.8
13Flathead River at Polson2.9
13Flathead River at Polson2.9
14Mission Valley0
14Mission Valley0
15Little Bitterroot River1.7
15Little Bitterroot River1.7
16Clark above Missoula2.1
16Clark above Missoula2.1
17Blackfoot River2.5
17Blackfoot River2.5
18Clark Fork above Missoula2.5
18Clark Fork above Missoula2.5
19Bitterroot River1.9
19Bitterroot River1.9
20Clark Fork River below Bitterroot River2.3
20Clark Fork River below Bitterroot River2.3
21Clark Fork River below Flathead River2.7
21Clark Fork River below Flathead River2.7
22Beaverhead River1
22Beaverhead River1
23Ruby River1.3
23Ruby River1.3
24Big Hole River1.5
24Big Hole River1.5
25Boulder River (Jefferson)0.8
25Boulder River (Jefferson)0.8
26Jefferson River1.9
26Jefferson River1.9
27Madison River1
27Madison River1
28Gallatin River2.1
28Gallatin River2.1
29Missouri River above Canyon Ferry1.6
29Missouri River above Canyon Ferry1.6
30Missouri River below Canyon Ferry0
30Missouri River below Canyon Ferry0
31Smith River2.2
31Smith River2.2
32Sun River1.4
32Sun River1.4
33Teton River1.8
33Teton River1.8
34Birch/Dupuyer2.1
34Birch/Dupuyer2.1
35Marias Below Tiber Reservoir2.6
35Marias Below Tiber Reservoir2.6
36Musselshell River2.8
36Musselshell River2.8
37Missouri River above Fort Peck0.7
37Missouri River above Fort Peck0.7
38Missouri River below Fort Peck2.4
38Missouri River below Fort Peck2.4
39Milk River2.9
39Milk River2.9
40Dearborn2.1
40Dearborn2.1
41Yellowstone River above Livingston2.2
41Yellowstone River above Livingston2.2
42Shields River2.6
42Shields River2.6
43Boulder River (Yellowstone)3.1
43Boulder River (Yellowstone)3.1
44Stillwater River1.7
44Stillwater River1.7
45Rock/Red Lodge Creeks0
45Rock/Red Lodge Creeks0
46Clarks Fork River2.6
46Clarks Fork River2.6
47Yellowstone River above Bighorn River2.3
47Yellowstone River above Bighorn River2.3
48Bighorn River below Bighorn Lake1.4
48Bighorn River below Bighorn Lake1.4
49Little Bighorn River1.2
49Little Bighorn River1.2
50Yellowstone River below Bighorn River1.9
50Yellowstone River below Bighorn River1.9
51Tongue River2.4
51Tongue River2.4
52Powder River1.7
52Powder River1.7
53Upper Judith River3.6
53Upper Judith River3.6
54Saint Mary River2.8
54Saint Mary River2.8