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Cascade Groundwater Alliance

  • The City and Rockwood Water People’s Utility District formed the Cascade Groundwater Alliance to expand Gresham’s groundwater system together. The new water system is under construction and will be complete in 2026.   

  • Tap Chat virtual open house

    If you missed the Tap Chat virtual open house, you can watch the recording on YouTube.

    Benefits of the Cascade Groundwater Alliance  

    • More consistent water quality.  
    • Lower long-term water rates. 
    • Better earthquake-resistant reservoirs and pipes.  
    • More control of water policy decisions.
    • Why Groundwater?
    • What is Groundwater?
    • Groundwater Treatment
    • Resources
    • Contact
    Why Groundwater?

    The cost to produce groundwater is significantly less than purchasing the same amount of water from Portland in the future. 

    Historic partnership is expanding our water system


    The City purchases water from the City of Portland. Portland runs and operates the Bull Run surface water system. Federal rules now require Portland to treat Bull Run surface water to protect it from microbial pathogens. 

    • Portland will build a new filtration facility by September 2027. 
    • A new Bull Run water filtration facility is estimated to cost between $850 million and $1.2 billion. 
    • Projections show future rate increases to cover the new treatment facility costs. 
    • Cost of construction is shared by all customers, including Gresham. 

    The value of groundwater

    City residents will benefit from smaller rate increases thanks to a transition to groundwater. 

    • Groundwater is clean, reliable and consistent. 
    • Groundwater is less impacted by earthquakes and fires, making it a safer water source in emergencies. 
    • Council approved the Groundwater Master Plan after extensive analysis and outreach to the community.  
    • Gresham residents already drink groundwater. The City pumps water from an existing groundwater well system in the Cascade Well Field during peak demand when the Bull Run reservoir is low. 

    Hydrogeologists confirm there is enough replenishable water in the Sand and Gravel Aquifer to supply Gresham residents.

    What is Groundwater?
    1. Groundwater is fresh water (from rain/snow) that soaks into soil and is stored in and moves slowly through soil, sand and rocks – called aquifers.  
    2. Gresham’s future groundwater comes from the Sand and Gravel Aquifer, located approximately 600-1200 feet below the surface. See a visual representation of the aquifer.
    3. The Sand and Gravel Aquifer is a large, sustainable and confined aquifer. 
    4. This aquifer currently supplies drinking water to Portland, Vancouver, Fairview, Wood Village and Troutdale. 
    5. A well – a pipe in the ground – is drilled into the aquifer. This fills with groundwater and is brought to the surface by a pump, and after treatment, will be ready to drink.
    Groundwater Treatment

    As a public supplier of drinking water, the water we supply is highly regulated to meet drinking water standards set by both federal and state requirements. 

    • Gresham tests and treats groundwater from existing wells. 
    • Our treatment facility will be upgraded to ensure water quality standards.
    • The City will expand our groundwater protection program to limit surface contamination. Water is pumped 600-1200 feet below ground making contamination from the surface less likely. 
    • Gresham conducted a pilot program and study in 2018 to test for and treat manganese, a natural mineral element. The planned treatment facility will filter manganese using chlorine. 
    • There is a minute amount of radon in groundwater sources. Gresham hired a consultant to evaluate ground water quality, including any presence of radon. The sampling data concluded radon levels are low and do not present a risk.  
    • In 2020, Gresham conducted a pilot study to determine the best water treatment methods that would exceed federal requirements.




    Coming soon 

    Water quality

    The City manages water quality programs to protect and monitor drinking water. 


    For more information, contact the Department of Environmental Services at 503-618-2525.

    • Well drilling at Kirk Park

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    • In 2020, the City drilled a new well at Kirk Park. The Kirk Park well will have the capacity to supply up to 4 million gallons of water per day.