HYDROLOGIC INVESTIGATION OF KARSTIC AQUIFERS: SAN SOLOMON SPRINGS GROUP, FAR WEST TEXAS

Recent oil and gas discoveries in the southern Delaware Basin have raised awareness of the San Solomon Springs group, a series of six environmentally sensitive karst springs that discharge groundwater from Cretaceous limestones along the northeast flank of the Davis Mountains in far west Texas. The springs and related groundwater provide water resources for much of the agricultural activity in the area, as well as municipal water supply for the town of Balmorhea. The main San Solomon Spring is the centerpiece of Balmorhea State Park. The springs also provide habitat for several federally listed endangered species of fish. The San Solomon Springs are located at the far western edge of the Edwards Plateau, one of the largest karst regions in the United States, and lie within the boundaries of several regional investigations of the greater Edwards-Trinity Aquifer system. However, a review of historical investigations of the region indicates that the San Solomon Springs are only indirectly associated with the Edwards-Trinity Aquifer. Springs in the Balmorhea area are in fact part of a different hydrologic regime more closely associated with carbonate aquifers in the Apache Mountains, and with recharge areas in the southern Salt Basin almost 100 km to the west.

A dye trace study conducted by personnel with the National Cave and Karst Research Institute has established a connection between Phantom Lake Spring Cave, the farthest upgradient spring, and spring discharge at Balmorhea State Park, at a minimum flow rate of ~1000 m/day. Based on this work, a more comprehensive dye trace investigation has been proposed, as well as a series of water level measurements, sampling for water chemistry analysis, and near-surface geophysical surveys to better characterize conduit flow within the karstic aquifer that feeds the San Solomon Springs group.