Last year, the State Water Resources Control Board’s (State Board) adopted a maximum contaminant level (MCL) for 1,2,3-Trichloropropane (TCP) at 5 parts per trillion (ppt). On January 31, the State Board held a meeting to provide an overview of monitoring and testing requirements.

Summary of New Requirements for Community and Nontransient-Noncommunity Water Systems:

  • Monitor sources for 1,2,3-TCP and comply with the 5ppt MCL;
  • Report all sampling results;
  • Data substitution: 1,2,3-TCP water quality monitoring data collected within the two years prior to the date of the MCL may be eligible for initial monitoring requirements;
  • Granular Activated Carbon (GAC) has been identified as the Best Available Technology (BAT);
  • Water Systems that violate the MCL are required to use specific Consumer Confidence Report languag

For a complete list of requirements, please visit the Division of Drinking Water’s webpage by clicking here.

Initial Quarterly Sampling:

  • Initial monitoring began in January, 2018 (January, February, and March);
  • Data substitution results from groundwater samples collected during 2016 and 2017 may be eligible for up to three of the four quarters of initial monitoring;
  • Each individual source must be sampled – composite samples are not allowed.

Testing waivers are handled by the local Drinking Water Office or Local Primacy Agency.

To download a copy of the presentation, click here.

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