When we see chloride spikes in the wintertime, it confirms our suspicions that road salt is in fact contributing to chloride pollution in local waterways. Chloride can linger or persist in the environment after being applied, so it isn’t unusual to see slightly elevated chloride levels throughout the year. Each year that road salt is applied, those chloride levels can increase.

However, outside of the winter season, it isn’t incredibly common to see chloride levels elevated to at or above toxic conditions for freshwater organisms - unless there is a drought event, the groundwater is contaminated, or there is a continuous source of chloride pollution (which could be something other than road salt).

In Cleveland, Ohio, in May 2024, we are seeing just that—elevated levels of chloride pollution persisting through the spring at most of the sites monitored by Cleveland Metroparks (you can see more of the monitoring results below for some of the sites).

Wolf Creek, Cleveland, OH

Heider Creek at the mouth - direct tributary to Lake Erie

Tributary to Chippewa Creek on Meadows Drive

Euclid Creek, Beachwood, OH

What could be causing the elevated salt levels in and around Cleveland? There could be a few possibilities:

• The chloride likely isn’t coming from Lake Erie, as most (if not all) of the waterways tested are running north into the Great Lake. (Check out this neat application to see where water goes if you drop a raindrop.)


• It is possible that road salt was excessively applied during the winter months and the levels measured in the results are reflecting the persistence of road salt after it enters the environment.


• Groundwater contamination is possible for sites that have a nearby groundwater discharge source and show elevated chloride results year-round.


• There could be uncovered or badly placed road salt piles that are releasing chloride into the environment (especially during and after rain and thaw events).


• The elevated levels could be a combination of road salt pollution and another source of chloride pollution, such as sewage effluent, water softener discharge, fertilizers, processing plant discharge, and more!


• Another possibility might even be salt from a nearby salt mine somehow contaminating local waterways.

We won’t be able to narrow down the source without more testing.

If you want to be part of the solution and help us to pinpoint road salt pollution problems in waterways you care about, join Salt Watch! Also, be sure to check out the Clean Water Hub to view Salt Watch data in your area.

Request a free Salt Watch kit today