May 1996
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 Reservoir1.5
1Marias Above Tiber Reservoir1.5
2Tobacco2
2Tobacco2
3Kootenai to Libby Dam2.2
3Kootenai to Libby Dam2.2
4Kootenai River below Libby Dam1.2
4Kootenai River below Libby Dam1.2
5Fisher River-0.4
5Fisher River-0.4
6Yaak River0.7
6Yaak River0.7
7North FK. Flathead River1.8
7North FK. Flathead River1.8
8Middle FK. Flathead River1.7
8Middle FK. Flathead River1.7
9South FK. Flathead River1.2
9South FK. Flathead River1.2
10Flathead at Columbia Falls1.5
10Flathead at Columbia Falls1.5
11Stillwater/Whitefish Rivers1.9
11Stillwater/Whitefish Rivers1.9
12Swan River1.1
12Swan River1.1
13Flathead River at Polson1.8
13Flathead River at Polson1.8
14Mission Valley1.4
14Mission Valley1.4
15Little Bitterroot River0.9
15Little Bitterroot River0.9
16Clark above Missoula1.4
16Clark above Missoula1.4
17Blackfoot River1.7
17Blackfoot River1.7
18Clark Fork above Missoula1.6
18Clark Fork above Missoula1.6
19Bitterroot River2
19Bitterroot River2
20Clark Fork River below Bitterroot River1.7
20Clark Fork River below Bitterroot River1.7
21Clark Fork River below Flathead River1.8
21Clark Fork River below Flathead River1.8
22Beaverhead River1.8
22Beaverhead River1.8
23Ruby River0.7
23Ruby River0.7
24Big Hole River2.2
24Big Hole River2.2
25Boulder River (Jefferson)0.2
25Boulder River (Jefferson)0.2
26Jefferson River1.8
26Jefferson River1.8
27Madison River1.7
27Madison River1.7
28Gallatin River1.1
28Gallatin River1.1
29Missouri River above Canyon Ferry1.6
29Missouri River above Canyon Ferry1.6
30Missouri River below Canyon Ferry1
30Missouri River below Canyon Ferry1
31Smith River0.7
31Smith River0.7
32Sun River1.4
32Sun River1.4
33Teton River1.9
33Teton River1.9
34Birch/Dupuyer1.9
34Birch/Dupuyer1.9
36Musselshell River0.4
36Musselshell River0.4
37Missouri River above Fort Peck1.7
37Missouri River above Fort Peck1.7
38Missouri River below Fort Peck1.7
38Missouri River below Fort Peck1.7
39Milk River0.3
39Milk River0.3
41Yellowstone River above Livingston3
41Yellowstone River above Livingston3
42Shields River1
42Shields River1
43Boulder River (Yellowstone)2
43Boulder River (Yellowstone)2
44Stillwater River2.5
44Stillwater River2.5
45Rock/Red Lodge Creeks3
45Rock/Red Lodge Creeks3
46Clarks Fork River3.2
46Clarks Fork River3.2
47Yellowstone River above Bighorn River3
47Yellowstone River above Bighorn River3
48Bighorn River below Bighorn Lake0.9
48Bighorn River below Bighorn Lake0.9
49Little Bighorn River0
49Little Bighorn River0
50Yellowstone River below Bighorn River2.1
50Yellowstone River below Bighorn River2.1
51Tongue River1
51Tongue River1
52Powder River0.9
52Powder River0.9