May 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 Reservoir1.9
1Marias Above Tiber Reservoir1.9
2Tobacco0.9
2Tobacco0.9
3Kootenai to Libby Dam0.6
3Kootenai to Libby Dam0.6
4Kootenai River below Libby Dam0.3
4Kootenai River below Libby Dam0.3
5Fisher River1.1
5Fisher River1.1
6Yaak River3
6Yaak River3
7North FK. Flathead River1.1
7North FK. Flathead River1.1
8Middle FK. Flathead River1.1
8Middle FK. Flathead River1.1
9South FK. Flathead River0.3
9South FK. Flathead River0.3
10Flathead at Columbia Falls0.8
10Flathead at Columbia Falls0.8
11Stillwater/Whitefish Rivers0.6
11Stillwater/Whitefish Rivers0.6
12Swan River-0.3
12Swan River-0.3
13Flathead River at Polson0.5
13Flathead River at Polson0.5
14Mission Valley-0.2
14Mission Valley-0.2
15Little Bitterroot River-0.8
15Little Bitterroot River-0.8
16Clark above Missoula0.7
16Clark above Missoula0.7
17Blackfoot River0.6
17Blackfoot River0.6
18Clark Fork above Missoula0.6
18Clark Fork above Missoula0.6
19Bitterroot River1
19Bitterroot River1
20Clark Fork River below Bitterroot River0.7
20Clark Fork River below Bitterroot River0.7
21Clark Fork River below Flathead River0.6
21Clark Fork River below Flathead River0.6
22Beaverhead River0.7
22Beaverhead River0.7
23Ruby River-0.7
23Ruby River-0.7
24Big Hole River1
24Big Hole River1
25Boulder River (Jefferson)-0.3
25Boulder River (Jefferson)-0.3
26Jefferson River0.7
26Jefferson River0.7
27Madison River0.3
27Madison River0.3
28Gallatin River-0.6
28Gallatin River-0.6
29Missouri River above Canyon Ferry0.3
29Missouri River above Canyon Ferry0.3
30Missouri River below Canyon Ferry-0.2
30Missouri River below Canyon Ferry-0.2
31Smith River0.9
31Smith River0.9
32Sun River0.1
32Sun River0.1
33Teton River0.8
33Teton River0.8
34Birch/Dupuyer1.7
34Birch/Dupuyer1.7
36Musselshell River0.7
36Musselshell River0.7
37Missouri River above Fort Peck0.1
37Missouri River above Fort Peck0.1
38Missouri River below Fort Peck0.3
38Missouri River below Fort Peck0.3
39Milk River-0.7
39Milk River-0.7
41Yellowstone River above Livingston2
41Yellowstone River above Livingston2
42Shields River-0.9
42Shields River-0.9
43Boulder River (Yellowstone)0.4
43Boulder River (Yellowstone)0.4
44Stillwater River0.4
44Stillwater River0.4
45Rock/Red Lodge Creeks-0.5
45Rock/Red Lodge Creeks-0.5
46Clarks Fork River0.4
46Clarks Fork River0.4
47Yellowstone River above Bighorn River1.3
47Yellowstone River above Bighorn River1.3
48Bighorn River below Bighorn Lake2.7
48Bighorn River below Bighorn Lake2.7
49Little Bighorn River-0.6
49Little Bighorn River-0.6
50Yellowstone River below Bighorn River1.9
50Yellowstone River below Bighorn River1.9
51Tongue River-0.5
51Tongue River-0.5
52Powder River0.1
52Powder River0.1
999Kootenai at Ft. Steele0.6
999Kootenai at Ft. Steele0.6