The following types of data are often useful:
Basic water requirements data, categorized by sector and/or specific water users
Existing water use studies for the study area, and data from national, state, county or municipal agencies
Population projections for cities and towns, production activity level projections for industry and agriculture
Water consumption (water consumed by a demand site that is lost to the system, lost to evaporation, embodied in products, or otherwise unaccounted for)
Note: Agricultural irrigation demands can either be calculated using activity levels and water use rates as described above, or by simulating catchment processes such as evapotranspiration, runoff, infiltration and irrigation demands. See Overview of Catchment Calculation Methods for more information.