Including San Solomon Springs at Balmorhea State Park
Published: November 3, 2016
By: Tom Myers, Ph.D.
A large regional flow system combined with local recharge supports groundwater discharge from the Balmorhea Springs complex, including San Solomon Springs at Balmorhea State Park.
The regional flow system begins south of the Davis Mountains but flows northwest to near the Delaware Mountains where it curves southeast and flows back to the spring complex. Faults control the flow system by forcing groundwater to the surface through natural pathways from underlying bedrock aquifers to the surface or to shallow alluvial aquifers. The underlying bedrock aquifers are up to a couple thousand feet deep. Local recharge into shallow alluvial aquifers mostly from runoff from the Davis Mountains also supports the spring discharge, causing significant flow increases and decreasing the natural baseflow salinity. Due to irrigation development in the area, the current average spring flow is about 33,000 acre-feet/year (af/y), down from about 38,000 af/y about 80 years ago.
Unconventional oil and gas development could occur in geologic formations consisting of shale or very fine sand from 10,000 to 12,000 feet beneath the ground surface. This development could negatively affect water quality of the Balmorhea Springs primarily by leaks from well bores affecting the deep groundwater flow pathways within several miles of the springs. Fluids, both gas and liquids, could reach shallow aquifers that feed the springs. Long-term (greater than ten years) risks to the springs occur from hydraulic fracturing within the general area, which could be estimated as far as five to ten miles from the springs due to the potential long-term horizontal transport from the formations developed for oil and gas through faults to the surface These risks are not quantifiable but the probability that contamination will occur is significant. Surface spills would likely impact the springs at some point in the future if development occurs very near the springs along pathways through which contaminants could flow to the springs. Water use that occurs anywhere along the flow path supporting the springs could decrease the spring flows in addition to that expected due to planned development. An increase in hydraulic fracturing near the springs could increase the frequency of earthquakes which could impact water quality at the springs, as occurred in 1931, or affect groundwater flows by disrupting the pathways from the bedrock to the spring discharge point.
The shallower target formations near and southwest of the springs are not as desirable for oil and gas development as they are further north within Reeves County because of their heterogeneity. Recent acquisitions in deeper formations suggest that there will be at least additional exploratory development near Balmorhea.