Water use technical efficiency (WUTE) and three definitions of water use economic efficiency (WUEE) were estimated for the four river sub-basins that encompass the 13 irrigation districts in Southern Alberta over a 5-year period: 2004–08. The average level of WUTE varied from 3.5 to 6.2 Mt dam−3. The gross economic value of crop production varied from Canadian (C)$345 to C$592 dam−3. The net economic value of crop production varied from C$163 to C$268 dam−3. The incremental increase in net value of crop production under irrigation over what it would have been under dry land conditions varied from C$130 to C$199 dam−3. Results indicated a relatively high degree of correlation among the three measures of WUEE. Since about three-quarters of the water consumed in the four sub-basins in Southern Alberta is used for irrigating crops, increasing WUEE will be critical for meeting growing demand from predicted increases in economic activity, population growth and environmental needs.