The Influence of Step-Pools on Water Chemistry: San Juan Mountains, Colorado

Abstract

The number of streams in the United States with poor water quality conditions continues to increase each year. With a spike in the number of streams needing water quality improvements, new ways of stream health remediation are becoming more necessary than ever. A water quality analysis was conducted on step-pool sequences in the San Juan Mountains, Colorado to determine whether or not they have a potential to improve stream health. Six creek sites surrounding the Uncompahgre River were tested for all of the following chemical and physical characteristics. The chemical characteristics tested were: pH, conductivity, total dissolved solids, dissolved oxygen, nutrients (nitrate-nitrogen and phosphate), sulfate, and total iron and the physical characteristics tested were: step-pool depth, width, length, elevation, stream velocity and stream discharge. All of these characteristics were compared and analyzed to determine if step-pool sequences had an impact on the stream water quality in those six creeks. The analysis determined that 1). There was no statistical difference between the water quality in the streams before water passed through the step-pool sequences and after the water had passed through the step-pool sequences, 2). The location of the step-pool sequences on either side of the Uncompahgre River had a significant impact on nitrate-nitrogen, sulfate, total dissolved solids, and conductivity, and 3). There were relationships and patterns between a few of the physical and chemical characteristics within the step-pools. The overall result of the study indicates that though the step-pools may not improve the water quality in streams, relationships exist within the step-pools between the chemical and physical characteristics that should be further examined.