CLARC Cleanup Levels and Risk Calculations
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Please read the information contained in 'CLARC Overview' and 'Cautions and Limitations' before navigating this site.


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CLARC Overview

Cautions and Limitations

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Welcome to CLARC

Welcome to the Cleanup Levels and Risk Calculation (CLARC) tool, a searchable database developed and maintained by the Washington State Department of Ecology (Ecology). CLARC includes technical information related to the establishment of cleanup levels under the Model Toxics Control Act (MTCA) Cleanup Regulation, chapter 173-340 WAC. Ecology has compiled this technical information to help the user establish cleanup levels at a site. For an overview of the technical information contained in CLARC, please refer to the CLARC Overview. 

Note: CLARC has been updated to be consistent with the new rule amendments adopted by the Department of Ecology effective November 12, 2007. For more information, please see the guidance for applying toxicity equivalency factors (TEF) for selected environmental mixtures under MTCA.

New in April 2011: The CLARC Web application has been updated to reflect current toxicity information. Toxicity values were updated consistent with the hierarchy of information specified in the MTCA rule. Click here for Questions and Answers about this update. Click here to see details of CLARC update. In the absence of CLARC toxicity information and subject to Ecology approval, you may either use toxicity values from Tier 3 of EPA’s hierarchy of sources ( or develop your own in accordance with the MTCA rule. See also the History of Changes and the Guidance menu above for specific toxicological information. If you have questions or need assistance please contact Craig McCormack.

Caution: The use of CLARC alone is not sufficient to establish cleanup levels under the MTCA Cleanup Regulation, chapter 173-340 WAC. Please refer to 'Cautions and Limitations' before using CLARC.

Disclaimer: CLARC is not mandated by law, but rather is provided as a service to staff and the public. While the information provided in CLARC is extensive, it is not exhaustive and the user may need to obtain information from additional sources for certain hazardous substances. Although CLARC has undergone review to ensure the quality of the information provided, there is no assurance