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River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons

December 18, 2014

Chloride concentrations in northern U.S. included in this study have increased substantially over time with average concentrations approximately doubling from 1990 to 2011, outpacing the rate of urbanization in the northern U.S. Historical data were examined for 30 monitoring sites on 19 streams that had chloride concentration and flow records of 18 to 49 years. Chloride concentrations in most studied streams increased in all seasons (13 of 19 in all seasons; 16 of 19 during winter); maximum concentrations occurred during winter. Increasing concentrations during non-deicing periods suggest that chloride was stored in hydrologic reservoirs, such as the shallow groundwater system, during the winter and slowly released in baseflow throughout the year. Streamflow dependency was also observed with chloride concentrations increasing as streamflow decreased, a result of dilution during rainfall- and snowmelt-induced high-flow periods. The influence of chloride on aquatic life increased with time; 29% of sites studied exceeded the concentration for the USEPA chronic water quality criteria of 230 mg/L by an average of more than 100 individual days per year during 2006–2011. The rapid rate of chloride concentration increase in these streams is likely due to a combination of possible increased road salt application rates, increased baseline concentrations, and greater snowfall in the Midwestern U.S. during the latter portion of the study period.

Citation Information

Publication Year 2014
Title River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons
DOI 10.1016/j.scitotenv.2014.12.012
Authors Steven R. Corsi, Laura A. De Cicco, Michelle A. Lutz, Robert M. Hirsch
Publication Type Article
Publication Subtype Journal Article
Series Title Science of the Total Environment
Index ID 70135868
Record Source USGS Publications Warehouse
USGS Organization Wisconsin Water Science Center