A double-porosity model of ground-water flow in the Madera Formation based on spring hydrographs and aquifer test analyses from Placitas, New Mexico
— Peggy S. Johnson

The Pennsylvanian Madera Formation is a fractured carbonate aquifer of regional significance in the Sandia Mountains east of Albuquerque, New Mexico. Characterization of fractured aquifers is problematic due to the localized nature of ground-water flow. Spring hydrographs and aquifer test data indicate that ground water in the Madera aquifer moves as combined diffuse flow and fracture flow. Aquifer test drawdown data fit a double- porosity model, and show that ground water is primarily transmitted through large fractures, but the majority of aquifer storage is attributable to the limestone matrix. Fracture transmissivity ranges from 1840-2160 ft²/d. Total storativity, for both fractures and matrix, is 0.20-0.25. The fractures transmitting the bulk of spring discharge are associated with faults in the Madera Formation. Spring hydrographs from fault-controlled springs near the Village of Placitas may provide a potentially valuable source of data on Madera aquifer hydraulic properties, including effective porosity, transmissivity, storage, water budgets, and recharge. Further work is required before the full potential of spring hydrograph data can be utilized as a regional aquifer characterization tool in the Madera Formation.