Using Reference Springs to Describe Expected Flow, Temperature, and Chemistry Conditions for Geologically Related Groups of Springs

Reference springs can result in improved conceptual models of groundwater flow and an expanded understanding of the temporal variations in flow, temperature, and chemistry that may be expected for related springs. The reference spring concept is patterned off of the common practice of establishing reference sites to establish benchmark ecological conditions. We use the term "reference spring" to indicate a spring that is minimally disturbed and representative of a geologically related group of springs. Seven reference springs were selected from six previously defined groups that represent over 400 springs in Wisconsin, United States. Geologic cross-sections were constructed for each reference spring site, and springs were monitored for flow, spring-water temperature, and chemistry for up to 4 years, revealing new relationships within and between groups. Examples include: a range of temperature conditions that can be related to the depth of groundwater circulation for springs discharging from layered bedrock uplands, and differences in thermal patterns and specific conductance that can be related to the permeability and solubility of surficial glacial deposits for springs emanating from uneven glacial terrain. The results suggest that establishing reference springs may be a useful approach in other regions where geologically related groups of spring have been identified.