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Cascade Groundwater Alliance

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
  • Project Funding
Why Groundwater?

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


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. 
  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
  • 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.




  • Rockwood PUD, groundwater development master plan, executive summary

Water quality

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

Project information

Project team answers questions about the Cascade Groundwater Alliance

Project Funding

The Cascade Groundwater Alliance will share the cost to expand our water supply system.  Gresham will invest 70 million dollars over the next five years. 

Federal loan

Gresham and Rockwood Water PUD are receiving a federal WIFIA (Water Infrastructure Finance and Innovation Act) loan. This low-interest loan program provides favorable loan terms for large water improvement projects.   

Utility rate package

In September, Council approved a five-year water utility rate package, which went into effect Jan. 1, 2023. The rate increase covers water, stormwater and wastewater service. The water rate increase will help fund the expansion of our groundwater system. 

  • Rates typically increase every year; Council adopts a five-year rate package to provide cost certainty to businesses and residents.
  • This increase is significantly less than if the City had continued to purchase water from Portland.
  • We are committed to offering customers who qualify assistance with their water bills. The City will expand utility assistance and other tools to help customers with billing needs.

 Learn more about Gresham utility rates.

  • Senator Merkley at podium addressing a crowd at a groundbreaking event.
  • Three employees review plans, standing in front of a newly constructed water reservoir.

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  • The City applied for $58.8 million in WIFIA funding. "With this investment, we will save ratepayers millions of dollars on critical infrastructure improvements and ensure that the City of Gresham and Rockwood Water customers will have a sustainable water source for years to come," Sen. Jeff Merkley said.

    Photo: Sen. Merkley, creator of the national Water Infrastructure Finance and Innovation Act (WIFIA). 

  • The City of Gresham 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. Stay up to date at

  • 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. 

  • Rockwood Water increased water storage capacity with the construction of a new reservoir.