By Jennie Saxe
Is this winter over yet? Fortunately, we’ve had a few days in the mid-Atlantic that make me think spring could be just around the corner. Even as we prepare to turn the page weather-wise, some remnants of winter will stick around. This year, one of those remnants is salt…lots of salt.
A couple of years ago, we brought you some information on smart ways to apply salt to keep the roads safe in winter weather and protect water resources at the same time. While that winter was relatively mild, winter 2014 has been another story. Municipal salt supplies are running low, and recently it’s been tough to find “snow melt” of any kind in neighborhood hardware stores.
With the snow now melting, the leftover salt is headed right toward our water supplies. Here are some of the impacts that increased salt can have:
- Road salt runoff can increase levels of conductivity (a substitute measure of “saltiness”) in streams and cause stress to aquatic life like fish and macroinvertebrates – in high enough concentrations, salt runoff can be toxic to sensitive organisms
- Salt increases the density of water which impacts the normal turnover processes in waterbodies – this can also affect aquatic life through depleting oxygen levels in deeper water and nutrient supplies in the upper part of the water column
- Salt has more of an impact on freshwater systems than on those that are brackish or saline already
- Salty runoff that enters drinking water supplies could cause elevated sodium levels that can have health consequences
If you’d like to see how one of our local waters, the Schuylkill River, responds to road salt runoff, the US Geological Survey (USGS) has some interesting data. Salt runoff from roadways or salt blown by the wind could be responsible for that conductivity spike in mid-February. Since the chloride from road salt (sodium chloride) is not removed or transformed by natural processes, the only way to bring levels down is through dilution, usually by way of rainfall. Toward the end of February, you can see the conductivity levels decrease.
I’ve used some of our recent spring-like weather to sweep up the salt around our house. This will prevent even more salt from washing down the drain and into the creek near my house. Cities and towns can use street sweeping as a mechanism to remove excess salt from their streets at the end of the winter season.
Did you have any low-salt methods for handling the snow this winter? How are you keeping the left-over salt from getting into our waterways?
Dr. Jennie Saxe joined EPA in 2003 and is currently a Water Policy Analyst in the Water Protection Division of EPA Region 3 in Philadelphia. When not in the office, Jennie enjoys spending time with her husband and 2 children and cheering for the University of North Carolina Tar Heels.