From The Pueblo Chieftain (Chris Woodka):
“The Irrigation Improvement Rules are designed to allow improvements to the efficiency of irrigation systems in the Arkansas River Basin while ensuring compliance with the Arkansas River Compact,” [State Engineer Dick Wolfe] said in the court filing…
The rules would take effect on Jan. 1, 2011, and would apply only to surface irrigation improvements in the Arkansas River Basin made since 1999. The goal is to prevent the depletion of return flows to the Arkansas River which could be caused by things like sprinklers, drip irrigation systems and lining of canals. Under a draft set of rules proposed in late 2007, the burden of proving that improvements did not affect return flows fell entirely on irrigators. Several changes were made in the rules that removed some on-farm improvements, such as gated pipe or concrete lining of small ditches, from the rules during those meetings. The state also recognized the need for general permits within certain parts of the Arkansas Valley and agreed to take things like pond seepage into account. The state also developed a model that builds on engineering already accepted by Kansas to determine the impact of sprinkler systems based on their location in the Arkansas Valley, finding that on ditches with adequate water supplies, efficiencies could benefit the river, while improvements on water-short ditches could reduce return flows.
After the final committee meeting on the rules, farmers indicated they are still not convinced the loss of flows can be accurately measured and questioned some of the assumptions that are made in the state’s model. Wolfe countered that the model is flexible enough to accommodate changes if new data proves the assumptions wrong.