Multi-outlet spring systems can exhibit a variety of hydraulic interrelationships. At one extreme, all springs are “plumbed” together, which means the springs have a common source area. At the other extreme, none of the springs have common source areas and each spring is “plumbed” separately. In most circumstances, larger multi-outlet spring systems comprise some springs with common source areas and some springs with the differing source areas. Demonstrating that the source areas of individual springs in a multi-outlet spring system are the same or separate can be a challenge. This is because differences in flow quality and quantity resulting from the imprint by the source area by can be subtle. This challenge is especially vexing if the spring system has not been comprehensively studied. Such is the case of many, if not most, of the spring systems in west Texas.
The San Solomon Springs System at Balmorhea, Texas is an attractive site to study because it has six flowing springs and water from each spring has been sampled and chemically analyzed. To date, these chemical results have not been rigorously analyzed. A hydrochemical (i.e., ion concentrations and physiochemical parameters) and multi-isotope (i.e., oxygen-18, deuterium, carbon-13, boron-11, strontium-87) characterization of the San Solomon Springs System is used to support the conceptualization that different source areas contribute to a multi-outlet spring system.
This project showcased the utility of a multicomponent approach in characterizing source areas to a multi-outlet spring system. Results from these efforts identified that although spring hydrochemistry among all six springs is seemingly similar, statistically significant differences in ionic and isotopic compositions suggest multiple source areas recharge the San Solomon Springs System. Boron-11 is identified as a useful isotopic marker that should be explored further to differentiate between flow paths from natural and anthropogenic origins. Principal component analysis (PCA) is useful in delineating source areas and the constituents that account for variability in spring hydrochemistry. However, PCA does not provide details about where these source areas originate. The comprehensive approach of additional sampling, multivariate statistics, and geochemical modeling is necessary to establish that differences in spring hydrochemistry are persistent and not ephemeral.