THE YEARLY EFFECT OF SALTY STORM WATER ON A KEY WETLANDS HABITAT

Newpark Town Center is a high-density urban development with stormwater drains entering East Canyon Creek at the Swaner Nature Preserve wetland, near Park City City, Utah. At an elevation of 1800 meters, the study area receives 160 cm of snow for half the year and roads are salted during the snowy months. This study evaluates the impact of winter, spring, and summer stormwater runoff from Newpark Town Center to East Canyon Creek by conducting monthly water quality monitoring from January to August 2018. Four storm drains from Newpark Town Center and one runoff location from Interstate 80 were monitored in addition to an upstream location and downstream location. At the four sampled stormwater drains, total dissolved solids (TDS) values decreased from an average of 2300 mg/L in the winter and spring months (November, January, February, March, April) to an average of 1164 mg/L in the summer months (May, June, July, August). Dissolved oxygen (DO) concentrations decreased from an average of 6.38 mg/L during the winter months to an average of 2.56 mg/L in the summer months. Temperature increased from an average of 6.78 C during the winter months to an average of 12.7 C in the summer months. The average increase in TDS from upstream to downstream was 22.4 mg/L in the winter and spring, and an average increase of 70 mg/L during the summer. DO increases from upstream to downstream on an average of 1.4 mg/L in all seasons. Temperature, however, consistently increases downstream over the entire sampling period. Data collected from a USGS monitoring well 2 kilometers downstream of the study area indicates a pattern of increased TDS after snow events. The day following significant snowfall, TDS concentrations on average increase about 500 mg/L at the USGS monitoring station.. Based on the correlation between snowfall and increased TDS, we infer that the TDS change is from road salting. This elevated level of salt eventually dilutes, but over the course of 5 months (November to April). Our sampling area experiences increased TDS, temperature and DO readings at the downstream site versus the upstream throughout the entire year. The increase in temperature and TDS is likely due to the flow of salt and dust in the effluent from the storm water drains, especially during the winter and spring months.