Snow season is salt season in Illinois, from December to March public works crews will spend an enormous amount of effort keeping local roads and parking lots open for use.
Plow trucks are par of the winter urban landscape in Illinois (photo by Nick Nikola, SCWN)
A large part of those efforts involves the application of sodium chloride (salt) to transport surfaces. Salt has a number of properties that make it ideal for this purpose; under controlled conditions it can lower the freezing temperature of water to –6F and it is relevantly abundant. Without salt, delivering the winter driving conditions that we are used to would, for all practical purposes, be impossible. Currently public agencies spread over 53,000 tons of it a year in the Salt Creek watershed alone.
Salt use has costs beyond those incurred in purchasing and spreading it on thousands of miles of roadway. All that salt ends up in Salt Creek where it has major negative effects on the river. Surveys and analysis of the Salt Creek suggest that fish and macro invertebrate populations are negatively impacted when summer salt concentrations are greater than approximately 112 mg/l and 141 mg/l respectively. These effects are most likely indirect with salt impacting aquatic plant life rather than direct toxicity to fish or insects.
A truck applies salt brine to a road prior to a storm, a practice that can reduce the amount of salt used to keep roads open. (photo courtesy of the Village of Hanover Park)
High summer concentrations are not unusual in Salt Creek’s tributaries where lower water flow means less dilution. Winter monitoring has shown that chloride levels in Salt Creek peak during winter storms with concentrations of 1200 mg/l being recorded. Furthermore chlorides do not degrade as many other pollutants do, so how do we reduce water pollution from chlorides. The present strategy is to use less salt to get the job done. Techniques such as wetting salt before it’s applied to the streets have shown that the product works faster and reduces the amount of salt used. More advanced is the application of liquids (usually salt brine with a carbohydrate such as sugar beet added) to the roads prior to the storm, hence the dark lines some may have noticed on roads this winter. Both these techniques are becoming more common with public works departments throughout the region but private citizens should do their part also; be safe and prudent but be aware of where all that salt is ending up. Additional information on the impacts of salt on waterways and what can be done to reduce it can be found in the sensible salting for homeowners fact sheet. See also Effective Snow and Ice Removal for Homeowners.
You can do more to clean up the Salt Creek by printing and sending a copy of Chloride Fact Sheet for Public Works Staff to your town's Public Works Dept. and printing and sending a copy of Chloride Fact Sheet for Mayors and Managers to your town's Mayor or Manager.
Please ask them to check out the DuPage River Salt Creek Workgroup website for more information about ongoing efforts to clean up the Salt Creek.
This article was contributed by Stephen McCracken of DRSCW and edited by Christine Oszak of SCWN.