Health Risk Limits Rules for Groundwater 
SONARs

Below are Statements of Need and Reasonableness (SONARs) from previous years. Note: While SONARs contain information about why the guidance values were promulgated, they are written for a specific step in the rule development process. The SONAR will not show chemicals that were added or deleted during the rulemaking process and it does not reflect all information that was included in the final Health Risk Limit rule. For a current list of Health Risk Limits and other water guidance, please see the Human Health-Based Water Guidance Table.

2023/2024 SONAR and Appendixes (PDF)
Provides information about proposed HRL amendments in 2024.

2021/2023 SONAR and Appendixes A-D (PDF)
2021/2023 SONAR Appendixes E-F (PDF) 
2021/2023 SONAR Appendix G supplement to the SONAR, in response to the review by the Office of Administrative Hearings (PDF) 
Provides information about HRLs adopted in 2023.

2016/2018 SONAR (PDF)
Provides information about HRLs adopted in 2018.

2014/2015 SONAR (PDF)
Provides information about HRLs adopted in November 2015.

2012/2013 SONAR (PDF)
Provides information about HRLs adopted in September 2013.

2010/2011 SONAR (PDF)
Provides information about HRLs adopted in March 2011.

2008/2009 SONAR (PDF)
This SONAR provides a thorough description of the scientific methods and principles used to develop HRLs, in addition to describing HRLs adopted in 2008/2009. For definitions of terms, see the Health-Based Water Guidance Glossary (PDF)

1993 SONAR (PDF)
Contains information about HRLs adopted in 1993 and 1994.