Salinity Characterization and Source Assessment in the South Platte River Basin, Northeastern Colorado

Salinity in irrigation water withdrawn from the South Platte River in northeastern Colorado is impacting agriculture in the region. This study utilizes existing data to characterize the spatial and temporal changes in salinity within the river and to begin to identify the major sources of dissolved solids in the middle reaches of the South Platte River. A complete characterization of salinity and its sources in the basin is a necessary first step in identifying effective management and control strategies. Results of this study indicate that large jumps in electrical conductivity (EC) and dissolved solids load occur in some upstream segments of the study area, while in other segments the changes are much more gradual. The three major tributaries are major contributors to both the EC levels and dissolved solids load of the main stem. Municipal wastewater treatment plants are also shown to be a potentially significant source of dissolved solids load at downstream monitoring stations.