Portland's Bull Run water filtration plant has ballooned to $2.58 billion and won't deliver filtered drinking water until 2029, two years past its original deadline.

The project, first approved by Portland City Council in 2017 at an estimated $500 million, is the largest public works project in Portland's history, OPB reported Oct. 23. The plant will filter cryptosporidium, a diarrhea-causing parasite, from the Bull Run Watershed. The watershed supplies drinking water to roughly 840,000 people across the Portland metro area, according to the Portland Water Bureau.

That service area includes parts of Washington County. The Tualatin Valley Water District (TVWD), which serves Bethany, Cedar Mill and surrounding communities, has historically purchased Bull Run water from Portland. TVWD is now transitioning to the Willamette Water Supply System (WWSS), a new source that the district said will replace the water it has purchased from Portland.

Why costs climbed

The price tag has risen steadily: $1.5 billion in 2019, $1.8 billion in June 2023, $2.1 billion in 2024 and $2.58 billion in the current city budget, according to KATU and Water Bureau records.

The Water Bureau attributed the increases to pandemic-era inflation in construction materials, a complex land use permitting process and a construction pause in early 2025. The Oregon Land Use Board of Appeals sent one item from the project's permit back to Multnomah County in January 2025, halting work until the county reapproved the permit in June 2025. That delay set the construction schedule back about seven months.

A coalition of landowners and a conservation nonprofit have twice filed appeals against the project's permits, arguing the 95-acre site would diminish the state's inventory of agricultural land, OPB reported in February.

In May 2026, Portland and the Oregon Health Authority (OHA) signed a new compliance agreement extending the deadline from September 2027 to Sept. 30, 2029.

Rate impact

Portland water rates rose 8.1% effective July 2026, adding about $10.20 per month to a typical single-family residential bill, according to the Water Bureau. The city's finance team projected nearly 10% annual water rate increases through the early part of the next decade, KATU reported in April.

Portland City Councilor Mitch Green, the lone vote against authorizing $525 million in project debt at a public works committee hearing, warned the math adds up fast. Green said 9.8% annual increases sustained over seven years would double the rate, according to KATU.

Recently retired city administrator Mike Jordan predicted at a City Club event that the final cost would exceed $4 billion. The Water Bureau disputed that figure, telling KATU the claim was "inaccurate and not supported by current project information."

What the money covers

The $2.58 billion total covers the full Bull Run Treatment Program: $2.46 billion for the filtration project itself, $20 million for a completed corrosion control project and $101 million in program financing.

Two federal Water Infrastructure Finance and Innovation Act loans totaling about $1.05 billion are helping offset costs. The bureau said those loans will save ratepayers at least $387 million compared with other borrowing options.

The filtration plant is about 40% complete. The Water Bureau's compliance agreement with OHA requires filtered water to flow by Sept. 30, 2029.