Groundwater/Wellhead Protection

Wellhead Protection is a pro-active approach to preventing contamination of groundwater used for drinking water supplies. Cleaning groundwater can often cost 100 times more than preventing the pollution in the first place. 

Wellhead Protection (WHP) is a requirement for local governments to protect the health of people using groundwater supplies for drinking water. The City of Redmond WHP Program is compliant with Chapter 246-290 of the Washington Administrative Code (WAC) and, therefore, the federal Safe Drinking Water Act. 

Redmond’s Wellhead Protection Program staff evaluate and mitigate risks to groundwater by:

  • Identifying groundwater resources at risk surrounding our municipal supply wells (the Critical Aquifer Recharge Area). 
  • Identifying existing groundwater impacts and activities that have the potential to contaminate groundwater or reduce groundwater quantity.
  • Developing strategies to prevent degradation or loss of groundwater resources from occurring.
  • Monitoring to make sure a condition that could cause an unacceptable risk is not occurring.
  • Managing existing impacts to ensure appropriate investigation and cleanup of natural resources.

When a potential impact or supply risk is identified, Wellhead Protection Program staff then work closely with the Water/Wastewater Division to meet Source Water Protection regulations before a municipal supply well can be adversely impacted.

  1. Critical Aquifer Recharge Areas
  2. Groundwater
  3. Protecting Groundwater
  4. Monitoring Program

Redmond recently updated groundwater/wellhead protection areas using robust computer modeling. The updated areas are called Critical Aquifer Recharge Areas (CARA) and were adopted April 16, 2019.

As part of the update, Redmond convened a Sounding Board of people with diverse perspectives who learned about the groundwater model, participated in a series of meetings and helped make decisions related to some model settings.

CARA I and CARA II are areas are where the aquifer is vulnerable to contamination, and where infiltration is important for replenishing,CARA I II_City_Limit or recharging, the groundwater supply. These special protection areas are based on the time it takes for groundwater to travel to a municipal supply well.

  • CARA I represents the area where groundwater takes up to five years to travel to a municipal supply well.
    • This is the area where groundwater supply is most vulnerable to contamination from pollutants.
  • CARA II represents the area where groundwater takes up to 10 years to travel to a municipal supply well, plus additional sensitive areas.

CARA I and CARA II have requirements for development and businesses that help protect groundwater in CARA I and II. See Related Documents and Other Resources sections on this page for more groundwater information.


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