April 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 Reservoir1.4
1Marias Above Tiber Reservoir1.4
2Tobacco1.8
2Tobacco1.8
3Kootenai to Libby Dam1.8
3Kootenai to Libby Dam1.8
4Kootenai River below Libby Dam2
4Kootenai River below Libby Dam2
5Fisher River-0.5
5Fisher River-0.5
6Yaak River1
6Yaak River1
7North FK. Flathead River1.4
7North FK. Flathead River1.4
8Middle FK. Flathead River1.5
8Middle FK. Flathead River1.5
9South FK. Flathead River1.1
9South FK. Flathead River1.1
10Flathead at Columbia Falls1.3
10Flathead at Columbia Falls1.3
11Stillwater/Whitefish Rivers1.4
11Stillwater/Whitefish Rivers1.4
12Swan River0.7
12Swan River0.7
13Flathead River at Polson1.6
13Flathead River at Polson1.6
14Mission Valley1.1
14Mission Valley1.1
15Little Bitterroot River0.9
15Little Bitterroot River0.9
16Clark above Missoula0.7
16Clark above Missoula0.7
17Blackfoot River0.8
17Blackfoot River0.8
18Clark Fork above Missoula0.8
18Clark Fork above Missoula0.8
19Bitterroot River1.7
19Bitterroot River1.7
20Clark Fork River below Bitterroot River1
20Clark Fork River below Bitterroot River1
21Clark Fork River below Flathead River1.4
21Clark Fork River below Flathead River1.4
22Beaverhead River1.8
22Beaverhead River1.8
23Ruby River0
23Ruby River0
24Big Hole River2.1
24Big Hole River2.1
25Boulder River (Jefferson)0.7
25Boulder River (Jefferson)0.7
26Jefferson River1.7
26Jefferson River1.7
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 River0.9
31Smith River0.9
32Sun River1.4
32Sun River1.4
33Teton River1.8
33Teton River1.8
34Birch/Dupuyer2.2
34Birch/Dupuyer2.2
36Musselshell River1
36Musselshell River1
37Missouri River above Fort Peck1.8
37Missouri River above Fort Peck1.8
38Missouri River below Fort Peck1.6
38Missouri River below Fort Peck1.6
39Milk River1.6
39Milk River1.6
41Yellowstone River above Livingston3.4
41Yellowstone River above Livingston3.4
42Shields River0.9
42Shields River0.9
43Boulder River (Yellowstone)1.5
43Boulder River (Yellowstone)1.5
44Stillwater River1.8
44Stillwater River1.8
45Rock/Red Lodge Creeks3
45Rock/Red Lodge Creeks3
46Clarks Fork River3.3
46Clarks Fork River3.3
47Yellowstone River above Bighorn River3
47Yellowstone River above Bighorn River3
48Bighorn River below Bighorn Lake2.1
48Bighorn River below Bighorn Lake2.1
49Little Bighorn River0.9
49Little Bighorn River0.9
50Yellowstone River below Bighorn River2.8
50Yellowstone River below Bighorn River2.8
51Tongue River0.9
51Tongue River0.9
52Powder River0.3
52Powder River0.3