A data logger in Alewife Brook in Arlington, MA, tracks the impact of road salt application on chloride concentrations in the stream. High concentrations of chloride can be toxic to freshwater plants and animals.

Note the spikes in concentration as rain storms (Feb 2, Feb 16) wash accumulated salt from the streets directly to the stream.

Chloride concentration

Air temperature

Precipitation

Total Daily Precip

Flow

Location

The data logger is located near the intersection of Broadway and Alewife Brook Parkway (42.406819 lat, -71.134033 long).

Data sources

Specific conductance measurements (every 15 min) gathered by an Onset HOBO data logger in Alewife Brook in Arlington, MA. Chloride concentrations calculated using a regression developed by Mass DEP describing the relationship between specific conductance and chloride concentrations, published in Massachusetts Consolidated Assessment and Listing Methodology (CALM) Guidance Manual for the 2018 Reporting Cycle (MassDEP, 2018). https://www.mass.gov/files/documents/2018/05/07/2018calm.pdf

Chronic and acute toxicity thresholds taken from Ambient Aquatic Life Water Quality Criteria for Chloride (EPA, 1988). https://www.epa.gov/sites/production/files/2018-08/documents/chloride-aquatic-life-criteria-1988.pdf Guidelines specify that 4-day average Cl concentration should not exceed 230 mg/L more than once every three years on the average and the one-hour average concentration does not exceed 860 mg/L more than once every three years on the average.

Temperature and precipitation data downloaded from USGS gage at Fresh Pond, Cambridge, MA. https://waterdata.usgs.gov/usa/nwis/uv?422302071083801

Flow data downloaded from USGS gage at Alewife Brook, Arlington, MA. https://waterdata.usgs.gov/nwis/uv?site_no=01103025