Comparison of the power consumption coefficient (PCC) method to totalizing flow meter (TFM) for estimating ground-water pumpage in the Arkansas River Valley, Colorado

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In the mid-1990s, the Colorado Division of Water Resources (CDWR) adopted rules governing measurement of tributary groundwater pumpage for the Arkansas River Basin. The rules allowed groundwater pumpage to be determined using one of two approaches—power conversion coefficient (PCC) or totalizing flowmeters (TFM). In addition, the rules allowed a PCC to be applied to the electrical power usage up to 4 years in the future to estimate ground-water pumpage.

As a result of concerns about potential errors in applying the PCC approach forward in time, a study was done by the U.S. Geological Survey, in cooperation with CDWR and Colorado Water Conservation Board, to evaluate the variability in differences in pumpage between the two approaches, including the effects of time trends.