Issues Contributing Areas

Issues Contributing Areas (ICAs)

When a municipal water system operator can demonstrate in raw water (before treatment) that either a municipal well has a demonstrated exceedance of an Ontario Drinking Water Standard or an increasing trend of a contaminant, the Clean Water Act allows municipalities to designate wellhead protection areas as Issues Contributing Areas (ICA). An ICA is delineated identifying the area where activities and conditions as a result of past activities have or are likely to contribute to the elevated concertation of the substance in the well.

This allows activities to be deemed significant drinking water threats in a larger portion of a well head protection area than would normally be allowed.  For instance, sodium and chloride significant drinking water threats are typically present in vulnerability score ten, however, in an ICA, the significant drinking water threats can be designated in lower vulnerability scores. The designation of significant drinking water threats relates to whether risk management plans, prohibitions or mandatory education policies apply.  

In Wellington County, the Townships of Guelph/Eramosa, Centre Wellington, Puslinch and the Town of Erin all have ICAs established.

The different types of ICAs are listed below with examples of the associated Drinking Water Threats within these ICAs

• Chloride - storage of snow, handling and storage of road salt
• Sodium - storage of snow, handling and storage of road salt
• Nitrate - sewage systems, handling and storage of manure
• Trichloroethylene - waste disposal sites, handling and storage of Dense-Non-Aqueous Phased Liquids (DNAPLs)

To see where ICAs are located within the County, check out our mapping tool.