March 2008
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
1Marias Above Tiber Reservoir0
2Tobacco1.5
2Tobacco1.5
3Kootenai to Libby Dam0.2
3Kootenai to Libby Dam0.2
4Kootenai River below Libby Dam1.8
4Kootenai River below Libby Dam1.8
5Fisher River1.4
5Fisher River1.4
6Yaak River1.6
6Yaak River1.6
7North FK. Flathead River1.2
7North FK. Flathead River1.2
8Middle FK. Flathead River0.6
8Middle FK. Flathead River0.6
9South FK. Flathead River0.6
9South FK. Flathead River0.6
10Flathead at Columbia Falls1.1
10Flathead at Columbia Falls1.1
11Stillwater/Whitefish Rivers-9.9
11Stillwater/Whitefish Rivers-9.9
12Swan River-0.8
12Swan River-0.8
13Flathead River at Polson0.6
13Flathead River at Polson0.6
14Mission Valley-9.9
14Mission Valley-9.9
15Little Bitterroot River-9.9
15Little Bitterroot River-9.9
16Clark above Missoula1.1
16Clark above Missoula1.1
17Blackfoot River0.1
17Blackfoot River0.1
18Clark Fork above Missoula0.6
18Clark Fork above Missoula0.6
19Bitterroot River1.7
19Bitterroot River1.7
20Clark Fork River below Bitterroot River0.9
20Clark Fork River below Bitterroot River0.9
21Clark Fork River below Flathead River0.7
21Clark Fork River below Flathead River0.7
22Beaverhead River-0.1
22Beaverhead River-0.1
23Ruby River-0.7
23Ruby River-0.7
24Big Hole River0.7
24Big Hole River0.7
25Boulder River (Jefferson)-0.8
25Boulder River (Jefferson)-0.8
26Jefferson River1.3
26Jefferson River1.3
27Madison River0.9
27Madison River0.9
28Gallatin River1.5
28Gallatin River1.5
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 River0.5
31Smith River0.5
32Sun River0.7
32Sun River0.7
33Teton River1.1
33Teton River1.1
34Birch/Dupuyer-2.8
34Birch/Dupuyer-2.8
35Marias Below Tiber Reservoir0
35Marias Below Tiber Reservoir0
36Musselshell River-0.8
36Musselshell River-0.8
37Missouri River above Fort Peck-0.3
37Missouri River above Fort Peck-0.3
38Missouri River below Fort Peck-3
38Missouri River below Fort Peck-3
39Milk River0.6
39Milk River0.6
40Dearborn1.8
40Dearborn1.8
41Yellowstone River above Livingston1.7
41Yellowstone River above Livingston1.7
42Shields River-0.1
42Shields River-0.1
43Boulder River (Yellowstone)2
43Boulder River (Yellowstone)2
44Stillwater River0.5
44Stillwater River0.5
45Rock/Red Lodge Creeks-3.2
45Rock/Red Lodge Creeks-3.2
46Clarks Fork River2.1
46Clarks Fork River2.1
47Yellowstone River above Bighorn River1.6
47Yellowstone River above Bighorn River1.6
48Bighorn River below Bighorn Lake-0.2
48Bighorn River below Bighorn Lake-0.2
49Little Bighorn River0.3
49Little Bighorn River0.3
50Yellowstone River below Bighorn River-0.2
50Yellowstone River below Bighorn River-0.2
51Tongue River2.3
51Tongue River2.3
52Powder River1.7
52Powder River1.7
53Upper Judith River0.8
53Upper Judith River0.8
54Saint Mary River1.6
54Saint Mary River1.6