Most people and governments are supportive of and even promoting irrigation water use efficiency as a way to conserve water. Take an old gravity irrigation system applying 1000 gallons of water on an irrigated patch. This 65% efficient irrigation system will consumptively use (transpire and evaporate) only 650 gallons of the 1000 pumped and applied. The rest deep percolates below the root zone to rejoin the groundwater table (a non-consumptive use). So, 650 gallons are annually used consumptively (lost to the hydro system).
The irrigator is now paid a nice government incentive ($48K - $400 an acre on 120 acres - a typical Kansas incentive rate) to upgrade to a new, 90% efficient pivot so he can conserve water. He now pumps and applies only 850 gallons to the same patch - a 15% reduction (conservation). The new system now allows the crop to transpire and evaporate 90% of the pumped water while eliminating the inefficient water use (deep percolation) totally. This government incentive has just allowed the user to increase his consumptive draw on the aquifer from 650 gallons annually to 765 gallons each year (90% of 850 gallons). While inefficient water use is eliminated, and the pumped water is reduced 15%, the consumptive water use (CU) actually increases. Believe it or not, the change in the water table of a typical aquifer system changes as a result of consumptive water use, not gross pumpage. This conversion will actually increase the groundwater decline rate - all else being equal.
As if this were not bad enough, how many pivot conversions actually irrigated more acres than the original flood system? If land is available, we usually find a 15% increase in land when 15% more water becomes available due to efficiency improvements. And every newly irrigated acre increases consumptive use above the numbers discussed here.
Without clear and restrictive polices to control irrigated acres as system conversions are being made, consumptive use will tend strongly to increase as a result. And even if CU doesn't actually increase, it usually doesn't go down much at all. And even if it does happen to drop a bit, the system pays a premium for the 1-2% reduction which is easily offset by most of the other conversions that increase CU. This is a very inefficient way to seek water conservation.