Title: Lower Cienega Basin Source Water Study
Date: October 2000
Area: Lower Cienega Creek
Purpose: Research
Information reported: Water chemistry and stable isotope data
Format: Text (MS Word), GIS Coverages and Maps (ArcView), Graphs and Tables (MS Excel)
Cost: Call for current pricing
On-line availability: Lower Cienega Basin Source Water Study (PDF 1.02 MB)
REPORT SUMMARY
The purpose of this study was to determine the source of the surface water in Cienega Creek at the downstream end of the Cienega Creek Natural Preserve. The study methodology involved sampling water at two points along the creek, one point along Posta Quemada Creek (a tributary to Cienega Creek), and at a well near the end of the last perennial reach of the creek. Stable isotopes and water chemistry analyses were conducted on the samples. In addition to the sampling, PAG staff also conducted a geologic analysis to determine potential flow paths to help explain the sampling results. Additional unpublished data from other sources were analyzed. Tracer tests and hydrogeologic models were not used in this study. 

Results from the study include: 1) The water in Cienega Creek is not significantly influenced by surface or subflow from the Agua Verde/Posta Quemada creek system; 2) Stable isotopes in Cienega Creek and Del Lago Well water are similar, but the water chemistries are significantly different; 3) Tritium levels in the well water indicate recent recharge; 4) Interpretation of historic flows suggest that Cienega Creek recharges the aquifer tapped by the Del Lago Well; 5) Surface water in the last perennial reach of Cienega Creek seems to be derived from upstream Cienega Creek water.