From The Pueblo Chieftain (Chris Woodka):
The water will be used by the district to augment water under new rules requiring irrigators to prevent improvements from increasing consumptive use and depleting return flows. Rule 10 allows for group programs. The rules were adopted last year and apply to surface-fed sprinklers, drip irrigation systems and off-farm canal lining that could reduce return flows, possibly in violation of the Arkansas River Compact. Systems fed by wells are covered by 1996 rules adopted after a U.S. Supreme Court ruling against Colorado in a lawsuit brought by Kansas over the compact. The Lower Ark District, with the help of state grants, started a group program that allows farmers to pay a fee for basic engineering and calculation of deficits to the river.
More Arkansas River basin coverage here.