March 1999
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 Reservoir2.4
1Marias Above Tiber Reservoir2.4
2Tobacco1.3
2Tobacco1.3
3Kootenai to Libby Dam1.9
3Kootenai to Libby Dam1.9
4Kootenai River below Libby Dam0.5
4Kootenai River below Libby Dam0.5
5Fisher River2.4
5Fisher River2.4
6Yaak River2.7
6Yaak River2.7
7North FK. Flathead River1.4
7North FK. Flathead River1.4
8Middle FK. Flathead River2.5
8Middle FK. Flathead River2.5
9South FK. Flathead River1.1
9South FK. Flathead River1.1
10Flathead at Columbia Falls1.6
10Flathead at Columbia Falls1.6
11Stillwater/Whitefish Rivers1.4
11Stillwater/Whitefish Rivers1.4
12Swan River0.4
12Swan River0.4
13Flathead River at Polson0.9
13Flathead River at Polson0.9
14Mission Valley0.7
14Mission Valley0.7
15Little Bitterroot River1.4
15Little Bitterroot River1.4
16Clark above Missoula1.1
16Clark above Missoula1.1
17Blackfoot River1.3
17Blackfoot River1.3
18Clark Fork above Missoula1.2
18Clark Fork above Missoula1.2
19Bitterroot River2.1
19Bitterroot River2.1
20Clark Fork River below Bitterroot River1.4
20Clark Fork River below Bitterroot River1.4
21Clark Fork River below Flathead River1.1
21Clark Fork River below Flathead River1.1
22Beaverhead River1.2
22Beaverhead River1.2
23Ruby River0.1
23Ruby River0.1
24Big Hole River1.1
24Big Hole River1.1
25Boulder River (Jefferson)0.6
25Boulder River (Jefferson)0.6
26Jefferson River1
26Jefferson River1
27Madison River1.2
27Madison River1.2
28Gallatin River-0.3
28Gallatin River-0.3
29Missouri River above Canyon Ferry0.8
29Missouri River above Canyon Ferry0.8
30Missouri River below Canyon Ferry0.7
30Missouri River below Canyon Ferry0.7
31Smith River1.5
31Smith River1.5
32Sun River1.6
32Sun River1.6
33Teton River2.4
33Teton River2.4
34Birch/Dupuyer2.3
34Birch/Dupuyer2.3
36Musselshell River1.2
36Musselshell River1.2
37Missouri River above Fort Peck1.5
37Missouri River above Fort Peck1.5
38Missouri River below Fort Peck1
38Missouri River below Fort Peck1
39Milk River0.7
39Milk River0.7
41Yellowstone River above Livingston2.5
41Yellowstone River above Livingston2.5
42Shields River0.3
42Shields River0.3
43Boulder River (Yellowstone)0.6
43Boulder River (Yellowstone)0.6
44Stillwater River0.9
44Stillwater River0.9
45Rock/Red Lodge Creeks-0.2
45Rock/Red Lodge Creeks-0.2
46Clarks Fork River0.8
46Clarks Fork River0.8
47Yellowstone River above Bighorn River1.8
47Yellowstone River above Bighorn River1.8
48Bighorn River below Bighorn Lake1.9
48Bighorn River below Bighorn Lake1.9
49Little Bighorn River-0.7
49Little Bighorn River-0.7
50Yellowstone River below Bighorn River1.8
50Yellowstone River below Bighorn River1.8
51Tongue River-1.1
51Tongue River-1.1
52Powder River-0.1
52Powder River-0.1
999Kootenai at Ft. Steele1.7
999Kootenai at Ft. Steele1.7