DWQ Revised Interim Maximum Allowable Concentrations

The Division of Water Quality (DWQ) established revised Interim Maximum Allowable Concentrations (IMACs) as a part of the most recent triennial review. Some of these IMACs went into effect on August 1st, while others go into effect on October 1st 2010. These revised IMACs could affect how the results of fall groundwater monitoring events are evaluated this year, and going forward. The revised IMACs are as follows:



All these standards are either new, or lower than previous standards. The inorganic (metal) constituents will likely cause the most new detections above groundwater standards as these can be naturally occurring at higher concentrations than those listed as IMACs.

Please contact Joan Smyth, P.G. at 919-828-0577 x 221 or by email at joan@rsgengineers.com for further information regarding how these new standards may affect your groundwater monitoring.