Simulation of Aquifer System in Part of the Espaņola Basin, New Mexico

Development of three-dimensional numerical models of groundwater flow in part of the Española Basin, New Mexico, has utility for local and regional water supply assessments. The principal aquifer system of the modeled area consists of the Santa Fe Group. The primary water-bearing formations are the Tesuque Formation and the Los Alamos area main aquifer. The Tesuque Formation consists of interbedded deposits of sediments with contrasting permeability. The dip of the beds creates a preferential pathway for groundwater flow. That condition creates steep hydraulic gradients (50 to more than 100 feet per mile) where the movement of water is across, rather than parallel to, the strike of the dipping beds. Model analyses indicate that the dipping bed structure of the aquifer system significantly affects the groundwater flow system and its interconnection with surface water of the Rio Grande and its tributaries. Model analyses are presented with MODFLOW-2005 and MODFLOW-USG.

The Aamodt Litigation Settlement Act, signed into law on December 8, 2010 (Public Law 111-291, 124 STAT. 3134) provides for settlement of water rights claims in the Pojoaque basin, which is located within the Española Basin. The act allows for the annual diversion of up to 4000 acre feet per year from the Rio Grande and the construction of a regional water system to treat and distribute the water to residents of the basin. Options under consideration for development of the water system include alternatives for diversion of water from the Rio Grande and potential water management with aquifer storage and recovery. Models such as those presented here provide a means to understand and quantify the estimated area of hydrologic effect, which is necessary under general provisions of the New Mexico Groundwater Storage and Recovery Act (Title 19, Chapter 25, Part 8).