February 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 Reservoir3.2
1Marias Above Tiber Reservoir3.2
2Tobacco0.8
2Tobacco0.8
3Kootenai to Libby Dam1
3Kootenai to Libby Dam1
4Kootenai River below Libby Dam1.1
4Kootenai River below Libby Dam1.1
5Fisher River0.4
5Fisher River0.4
6Yaak River1.2
6Yaak River1.2
7North FK. Flathead River0.7
7North FK. Flathead River0.7
8Middle FK. Flathead River2.4
8Middle FK. Flathead River2.4
9South FK. Flathead River0.8
9South FK. Flathead River0.8
10Flathead at Columbia Falls1.3
10Flathead at Columbia Falls1.3
11Stillwater/Whitefish Rivers0.9
11Stillwater/Whitefish Rivers0.9
12Swan River0.4
12Swan River0.4
13Flathead River at Polson0.4
13Flathead River at Polson0.4
14Mission Valley0.1
14Mission Valley0.1
15Little Bitterroot River0.5
15Little Bitterroot River0.5
16Clark above Missoula0.7
16Clark above Missoula0.7
17Blackfoot River1.7
17Blackfoot River1.7
18Clark Fork above Missoula1.3
18Clark Fork above Missoula1.3
19Bitterroot River2.2
19Bitterroot River2.2
20Clark Fork River below Bitterroot River1.5
20Clark Fork River below Bitterroot River1.5
21Clark Fork River below Flathead River1.5
21Clark Fork River below Flathead River1.5
22Beaverhead River1.4
22Beaverhead River1.4
23Ruby River0.4
23Ruby River0.4
24Big Hole River0.8
24Big Hole River0.8
25Boulder River (Jefferson)0
25Boulder River (Jefferson)0
26Jefferson River0.8
26Jefferson River0.8
27Madison River0.7
27Madison River0.7
28Gallatin River-0.1
28Gallatin River-0.1
29Missouri River above Canyon Ferry0.6
29Missouri River above Canyon Ferry0.6
30Missouri River below Canyon Ferry0.7
30Missouri River below Canyon Ferry0.7
31Smith River1.9
31Smith River1.9
32Sun River2.7
32Sun River2.7
33Teton River2.9
33Teton River2.9
34Birch/Dupuyer3.2
34Birch/Dupuyer3.2
36Musselshell River1.5
36Musselshell River1.5
37Missouri River above Fort Peck1.7
37Missouri River above Fort Peck1.7
38Missouri River below Fort Peck1.1
38Missouri River below Fort Peck1.1
39Milk River1.3
39Milk River1.3
41Yellowstone River above Livingston1.9
41Yellowstone River above Livingston1.9
42Shields River-0.4
42Shields River-0.4
43Boulder River (Yellowstone)-0.2
43Boulder River (Yellowstone)-0.2
44Stillwater River-0.1
44Stillwater River-0.1
45Rock/Red Lodge Creeks0.6
45Rock/Red Lodge Creeks0.6
46Clarks Fork River0.6
46Clarks Fork River0.6
47Yellowstone River above Bighorn River1.2
47Yellowstone River above Bighorn River1.2
48Bighorn River below Bighorn Lake1.5
48Bighorn River below Bighorn Lake1.5
49Little Bighorn River-0.6
49Little Bighorn River-0.6
50Yellowstone River below Bighorn River1.4
50Yellowstone River below Bighorn River1.4
51Tongue River-0.6
51Tongue River-0.6
52Powder River-9.9
52Powder River-9.9
999Kootenai at Ft. Steele1.2
999Kootenai at Ft. Steele1.2