In response to a Colorado Supreme Court ruling, the Colorado Division of Water Resources passed new regulations requiring coal bed methane wells to be permitted as water wells and any water withdrawn from these wells be subject to Colorado’s water appropriation system. If the withdrawn water is tributary to the surface water system a plan to protect senior water rights holders is required (typically a substitute water supply plan followed by a water augmentation plan).
Several coal bed methane operators asked Norwest to evaluate the tributary nature of groundwater pumping from coal bed methane wells in a major coal bed methane producing basin in the State.
Norwest developed a calibrated numeric model of the groundwater flow systems from below the coal bed methane production zone up to the ground surface in order to evaluate the degree of interaction between groundwater and surface water. The model was used to delineate the tributary/ nontributary groundwater boundary in the producing formations and determine the degree of protection needed for existing water rights.
After submittal to the Division of Water Resources Norwest provided expert testimony and support of the model in adjudicatory hearings. The Colorado State Engineer ruled that the model and supporting testimony provided clear and convincing evidence of the tributary/ nontributary groundwater boundary for the basin. The clients were then able to develop a substitute water supply plan based on the modeled impacts to the surface water right holders.