Laboratory Certification & Low-level Mercury

Wisconsin DNR began recognizing laboratories' low-level mercury capabilities in 1997 in support of the Department's mercury strategy for wastewater permits. A provision in the Laboratory Certification Code, s. NR 149.12(2), Wis. Adm. Code, authorizes WDNR to recognize emerging analytical technologies when laboratories request recognition and those technologies meet the needs of the Department. DNR recognizes that it may not be necessary to use the most sensitive technique for all permit-related samples so facilities have some flexibility in selecting a laboratory. The Laboratory Certification Program maintains a listing of laboratories whose capabilities have been recognized. To be included in this list, the laboratory must be capable of quantifying mercury concentrations at or below 50 ng/L. Because laboratory detection limits vary, inclusion on the list does not mean that every listed laboratory has the capability to generate acceptable results for all compliance samples.

To report low-level mercury results to DNR, laboratories must be certified or registered for mercury under ch. NR 149 Laboratory Certification and then demonstrate their ability to meet performance-based criteria established by the Department. Although laboratories have flexibility in the method used, sample results must be quantifiable unless the sample concentration is below the water quality criterion. The laboratory must report results to their detection limit. See the related pages on this website for more information.