There are also many human sources of chloride, such as road salt, fertilizer, and animal waste. This makes chloride an excellent indicator of chemical and transport processes occurring in an aquifer. Map of Chloride in Minnesota's Ground Water Chloride concentrations can be elevated in different areas of the state, but concentrations increase from east to west. This is related to reduced recharge to ground water, increased residence times in ground water, and differences in geology from east to west. Concentrations of chloride were greatest in Cretaceous bedrock.
Cretaceous bedrock is enriched in minerals associated with seawater, including chloride.
Concentrations were also high in surficial Quaternary aquifers. Since these aquifers should be readily recharged and have low concentrations of chloride in the geologic material comprising the aquifer, the chloride is due to human activity. Fertilizer, road salt, and human waste are the most likely sources of chloride in these aquifers. If you have suggestions on how we can improve our service to you, please drop us a note. For more information about Minnesota, visit the Northstar Web site.