Anacortes, Washington Rebuilds Water Treatment Plant for Climate
Change
O epa .gov/arc-x/anacortes-washington-rebuilds-water-treatment-plant-climate-change
The city of Anacortes, WA recognized that its water
treatment plant, located along the Skagit River and
serving 56,000 people, was vulnerable to current floods
and future climate risks. In 2003, the city recognized the
need to update the facility from 21.4 million gallons of
water per day (mgd) to a stated capacity of 31.5 mgd.
Moving the facility out of the floodplain was deemed cost
prohibitive in 2008, so officials decided to rebuild on the
existing site. Such a strategy can be risky unless climate
projections are taken into account and adaptation
strategies implemented to reduce future vulnerability.
To determine the plant's vulnerability, Anacortes officials
worked with non-profit organizations to determine the
'best available' climate science and the associated impacts to the plant siting. A variety of climate risks were taken into account
including:
•	more frequent and intense storms
•	saltwater intrusion
•	increased sedimentation levels
Climate change impacts were projected through the 2080s and downscaled for the Skagit River area. These vulnerabilities
included an expanded 100-year floodplain, an estimated 350% increase in peak suspended sediment load in winter, and
anticipated upstream migration of the salt water wedge due to the effects of sea level rise.
In design and construction of this plant, officials sought to protect against higher risk of flooding by:
•	minimizing penetration below current 100 year flood elevation
•	raising critical electrical equipment out of the 100 year flood level
•	utilizing water proofing techniques below 40 foot elevation
•	designing ring dikes for flood protection
This plant was rebuilt on site at an expected cost of $56 million dollars and improvements to this design better prepare the
facility to meet increased service demand as well as projected changes in climate.
The New Anacortes Water Treatment Plant.
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How Did They Do It?
Applicable EPA Tools
Recognized climate risk and expected
vulnerability
•	Anacortes recognized the vulnerability of the
facility to flooding in 2003 and 2008, however
they also identified the cost prohibitive nature
of moving the facility.
•	When upgrading the facility they received
input from scientists and used downscaled
climate data to inform decision making.
Incorporated projections of climate	EPA's Climate Ready Water Utilities Adaptation Strategies Guide can
vulnerability within plant design to adapt to assist utilities in identifying low cost adaptation strategies to
future conditions	incorporate within plan designs.
•	Developed a design that acknowledged	EPA's Climate Ready Water Utilities Adaptation Strategies Guide
current vulnerability and sought to reduce
future vulnerability under anticipated future
conditions.
•	Elevated critical facility structures and
included ring dikes and dewatering pump
systems to protect against flooding.
•	Utilized water tight construction on the facility
and used water proof membrane below 40
foot elevation.
•	Designed to have no/minimal penetrations
below 100 year flood elevation and have
electrical switch gear located above 100 year
flood level.
•	Raised and strengthened levees near the
plant.
•	Increased sediment removal ability to deal
with expected increase from climate change
(although plant is still trying to quantify the
projected increase of sediment).
The EPA Coastal Inundation Toolkit can assist utilities in better
understanding facility vulnerability by illustrating a range of potential
sea level rise and storm surge scenarios.
EPA Coastal Inundation Toolkit
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How Did They Do It?
Applicable EPA Tools
Identified information gaps for future research The Climate Resilience Evaluation and Awareness Tool (CREAT)
helps utilities conduct traditional risk based or scenario based
Preliminary modeling suggests saltwater	vulnerability assessments to better understand information gaps and
intrusion is likely to be a future concern;	necessary future research,
additional analysis is planned.
• Further research is needed to better	The Climate Resilience Evaluation and Awareness Tool (CREAT)
understand the long term challenges
associated with sediment loads.
Similar Cases and More Information
To see how a community analyzed the impact of sea level rise on a water utility, view Manchester-by-the-Sea. For a community
that recognized the prohibitive cost of protecting a highly vulnerable facility and decided to move to a safer facility , see Iowa
City. Protecting the Blue Plains facility is only one of several strategies Washington, D.C. has taken to reduce the threat of
flooding on the community. To see how Washington, D.C. is using green infrastructure to reduce stormwater impacts and
combined sewer overflows view the DC Consent Decree.
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