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Water Resources Data System
1000 E. University Ave.
Laramie, WY 82071
Ph (307) 766-6651
Fax (307) 766-3785
Wyoming Surface Water Supply Index
The Surface Water Supply Index (SWSI) is computed using only surface water
supplies for the drainage. The computation includes reservoir storage, if
applicable, plus the forecast runoff. The index is purposely created to
resemble the Palmer Drought Index, with normal conditions centered near
zero. Adequate and excessive supply has a positive number and deficit water
supply has a negative values. Soil moisture and forecast precipitation are
not considered as such, but the forecast runoff may consider these values.