Water Resources Assessment, Pecos River Basin

SSP&A has supported the New Mexico Interstate Stream Commission (NMISC) on water resource management in the Roswell and Carlsbad Basins of New Mexico for nearly two decades. Recent efforts have included a significant extension (temporal, spatial), refinement, and calibration of a numerical groundwater model of the Roswell Basin, the analysis and simulation of the future climate and hydrology of the Pecos basin, and evaluation of relative impacts proposed water transfers may have on the Pecos River and shallow aquifer.

To assist the State in their management of water resources in the Carlsbad Basin, SSP&A developed a graphical user interface for evaluation of water rights transfer applications which integrates an existing superposition groundwater model and advanced applications of the Glover-Balmer and Theis equations for analysis of locations outside the active extents of the groundwater model. SSP&A provides optimization and support for augmentation wellfield operations, including annual reimbursements to irrigation users adjacent to NMISC augmentation wells. SSP&A has provided expert testimony on matters related to water resources, wellfield operations, and stream impacts.

Augmentation Pumping Management and Reimbursement Evaluations: NMISC operates an augmentation wellfield near Seven Rivers, New Mexico as part of its efforts to meet Pecos River flow requirements at the Texas Stateline. The augmentation pumping extracts groundwater from a shallow aquifer to augment flow of the Pecos River. As groundwater is extracted, water levels decline locally within the aquifer. This causes nearby agricultural users to experience water-level declines at their wells and increases their pumping costs. Each year, the superposition model is updated. The model is extended to include the most recent year, unit-response simulations are performed and transferred to a wellfield workbook which applies a convolution-integral approach to determine the augmentation-wellfield induced drawdown. and evaluated, then used to calculate pumping costs associated with augmentation-pumping drawdown and the required reimbursement amount.

Water Transfer Expert Support/Testimony: The State retained SSP&A to provide technical and litigation support for the transfer of NMISC purchased water rights in the Roswell basin, associated with the Lower Pecos Adjudication Settlement. These transfers involve evaluating the relative impacts of consumptive use and return flows at two locations, the “move-from” location and the “move-to” location. Specifically, SSP&A assessed impacts the transfer may cause to the Pecos River, the shallow aquifer, and the artesian aquifer; evaluated potential impairment to nearby wells of other ownership; and made determinations regarding any negative impact resulting from the transfer on the chloride concentration at the proposed wellfield location. To evaluate the impacts, SSP&A refined and updated the calibration on an existing numerical groundwater model for the Roswell Basin. The NMISC uses the results of the hydrological analyses to assess the transferability of the water right. In 2013, Dr. Barth provided expert testimony on matters related to water resources, wellfield operations and stream impacts.