Critical aquifer recharge areas

The goal of establishing critical aquifer recharge areas (CARA) is to protect a community’s drinking water by preventing pollution and maintaining supply. We help cities and counties comply with CARA requirements that are required by the state Growth Management Act.

Why does groundwater protection matter?

Washington state residents get at least 60 percent of their drinking water from groundwater. Most people in rural areas get their drinking water from groundwater.

What is our role?

We provide technical assistance and review for counties and cities to help them protect their groundwater. Cities and counties must identify where important groundwater resources are so they can protect their drinking water supply.

Protection of Critical Aquifer Recharge Areas is required under the Growth Management Act.

Help us improve our groundwater guidance

We are seeking feedback until May 7, 2021 on the updated draft Critical Aquifer Recharge Area guidance. This guidance helps local governments and residents understand what is required to protect groundwater resources under the Growth Management Act. Critical Aquifer Recharge Areas are considered Critical Areas because it protects groundwater that supplies local drinking water. Our guidance helps local governments plan and follow the state water quality standards.  

The current guidance is from 2005 (downloads document) and needed revision to reflect current laws, rules, and practices. We made revisions to: 

  • Reflect GMA laws and rules about Critical Areas amended since 2005.
  • Reflect outcomes of many cases that have been decided by the Growth Management Hearings Board and Superior Court since 2005.
  • Update resource links and references to websites and publications.
  • Maintain consistency with the Washington Department of Commerce Critical Areas Handbook accessible from their Critical Areas webpage.

Thank you to the many people who have already been involved in working to update the guidance. We started with a request for what we should update in the guidance and have our response to those comments in Appendix G of the new draft.

How can I comment? 

We will accept written comments on the guidance, from March 10, 2021 until 11:59 p.m. on May 7, 2021. Please have comments reference specific report text whenever possible.

You can submit comments:

Laurie Morgan
Water Quality Program
Washington State Department of Ecology
PO Box 47600
Olympia, WA  98504-7600


We held an online informational workshop on April 15, 2021, where we discussed the draft report and answered questions. For more information you can download the presentation we gave. 

Next steps

After the close of the comment period, we will consider and respond to comments, and include the final response to comments as an appendix to the final published report.

How to protect groundwater resources

The Growth Management Act defines CARAs as “areas with a critical recharging effect on aquifers used for potable water.” The following steps characterize where groundwater resources are important to understanding how to protect them.

  • Identify where groundwater resources are located.
  • Analyze the susceptibility of the natural setting where groundwater occurs.
  • Inventory existing potential sources of groundwater contamination.
  • Classify the how vulnerable the groundwater is to contamination events.
  • Designate areas that are most at risk to contamination events.
  • Protect groundwater by minimizing activities and conditions that pose contamination risks.
  • Ensure that contamination prevention plans and best management practices are followed.
  • Manage groundwater withdrawals and recharge impacts to:
    • Maintain availability for drinking water sources.
    • Maintain stream base flow from groundwater to support in-stream flows, especially for salmon-bearing streams.

We can provide technical assistance to local governments working to protect the functions and values of a community’s drinking water by preventing pollution and maintaining supply.

Our Critical Aquifer Recharge Areas Guidance Document helps you understand what is required for protecting local groundwater resources under the Growth Management Act.

Agricultural operations can help protect CARAs through the Voluntary Stewardship Program.