Seasonal Impact on Chloride Toxicity

Focus Area

Environmental Considerations in Planning








2-3 years

Research Idea Scope

Road salt runoff is a seasonal phenomenon, largely confined to the late-winter to spring months. For most northern biota, this is a lag period of growth when they are least susceptible to chlorides. The objective of this study is to determine chloride toxicity on key test organisms under real water chemistry conditions during various times of year to determine seasonal differences.

The first key task is to set up an in situ or competent model analytical system to measure chloride toxicity in selected organisms in real water conditions at four different seasonal periods. The second key task is to carry out the toxicity analyses over a season and duplicate the analysis over a second season.

Urgency and Payoff

The employment of road salt for winter maintenance has proven to be an extremely effective strategy for more than 50 years and will continue to be in the foreseeable future.  If we are to manage the application of salt properly, having a complete understanding of the impact of chloride runoff on our environment is critical and cannot be the subject of speculation.  The current methods of measuring chloride toxicity do not adequately reflect the character of the bodies of water we wish to protect.  The recent EPA-supported work in Iowa on the impact of water hardness and sulfates has shown the value of adding water chemistry to the chloride toxicity analysis.  The impact of seasonal variations in mobility, food sources, growth and metabolic phases may likewise have a significant impact upon an organism’s sensitivity to chlorides.

By carrying out this research, we will develop additional guidance on the effect of winter road salt generated chloride runoff upon local aquatic biota in order to better plan and manage the use of this strategic winter maintenance material.

Suggested By

Morton Satin, Salt Institute, 703-549-4648

[email protected]