Joint Comments on Perchlorate Reporting Jun 29, 2017 Comment Letters Agency: State Water Resources Control Board Subject: Association of California Water Agencies’ and California Municipal Utilities Association’s Comments Regarding the Detection Limit for Purposes of Reporting and Maximum Contaminant Level for Perchlorate Letter excerpt: ACWA and CMUA concur with DDW that lowering the DLR and then collecting new occurrence data at the lower DLR are reasonable steps towards revising the perchlorate MCL. ACWA and CMUA have several suggestions regarding these processes, as described below. DDW should develop a standardized approach for establishing a DLR.DDW should formally develop and standardize procedures, methods, and criteria in setting a DLR for a contaminant to ensure statistical rigor. These elements should include, at a minimum, quantified levels of precision and accuracy, as well as the percentage of commercial and non-commercial laboratories that can detect a concentration level of a contaminant. The majority of laboratories that perform perchlorate testing across California can meet the current DLR of 4 ppb. As such, DDW should determine what percentage of laboratories in California can meet a revised DLR closer to, equal to, or less than the PHG of 1 ppb for perchlorate. Development of a DLR should also account for intended use of the data. DLR data is used for a variety of reasons that should be considered in setting an appropriate limit. Data generated is used by water agencies to make decisions about treatment processes and sources of supply. Data is also used by water agencies to convey information to the public about the safety of their drinking water, including in annual Consumer Confidence Reports. Further, DLRs are important for water utilities that serve populations greater than 50,000 people in explaining contaminant occurrence in required triennial Public Health Goal Reports and for public meetings on these reports. The State Water Board also uses the data to determine compliance with drinking water standards. Therefore, having an appropriate DLR is important to ensure that data collected is reliable and credible. Download the joint comment letter
