Committee: Sabey data center would use a tiny share of Silver Lake industrial water
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Summary
Presenters told Butte‑Silver Bow’s ad hoc committee that the proposed Sabey data center would average roughly 16 million gallons a year (about 44,000 gallons a day), or about 0.2% of the industrial Silver Lake system’s sustainable capacity; staff said the industrial and potable systems are separate and potable supplies would not be affected.
Butte‑Silver Bow officials were told the Sabey data center’s planned cooling system would draw a small fraction of capacity from the Silver Lake (industrial) water system, and that the county’s potable supply would not be affected.
Jim Keenan, water plant superintendent for the city and county of Butte‑Silver Bow, and consultant/analyst Bob Morris presented maps, water‑rights summaries and recent consumption trends to the ad hoc committee. Keenan stressed that "the Silver Lake water system and the potable drinking water system are 2 separate independent systems." Morris summarized the arithmetic: the industrial system’s sustainable average capacity is roughly 25,000,000 gallons per day; last year industrial users collectively put about 2,500,000 gpd into the pipeline; Sabey’s projected use was presented as about 16,000,000 gallons per year (about 44,000 gpd), which Morris said is "a very, very light load on that industrial water system." (Morris also referenced a rounded figure of 40,000 gpd earlier in the presentation; staff described the 16 million‑gallon number as a full‑build estimate.)
Why it matters: the distinction between industrial and potable systems determines whether the county’s household supply could be affected. Keenan and Morris told the committee the potable system serves Butte from sources (Big Hole River, Basin Creek Reservoir and Moulton Reservoir) separate from Silver Lake, and therefore Sabey’s industrial withdrawals would not draw on the potable water system.
Details and context: Keenan reviewed the system’s history and physical capacity, including the Myers Diversion intake west of Anaconda, the 30‑mile transmission pipeline, and storage figures (Silver Lake gross capacity ~17,105 acre‑feet; the county holds about 13,138 acre‑feet of storage rights). He said earlier high‑use years were driven mainly by Montana Resources and that the system has previously met multi‑million‑gallon daily demands without drawing on storage in many years. Morris noted the proposed data‑center cooling design is a closed‑loop, dry‑first adiabatic system that uses water only under defined hot conditions (misters enabled above about 80°F) and that most days in Butte would rely on air cooling.
Committee questions and staff caveats: committee members asked about seasonality, whether the 44,000 gpd is a peak or average number, and whether buildout multiplies the figure. Morris responded that the presented totals are full‑build estimates and that most use would be concentrated in warmer periods; Commissioner Russell O’Leary asked for a usage profile by month. Staff noted that while rights on paper sum to a larger amount (the presentation cited a theoretical 57 cfs), actual creek flows vary and allocations and storage operations determine practical availability.
What remains unresolved: committee members asked for verification of vendor engineering and for a more detailed seasonal profile of the projected withdrawals. Staff also advised they would follow up on cross‑connection protections and formal allocation agreements if the project advances.
Next steps: the committee assigned follow‑ups to verify vendor water‑quality practices, to produce a month‑by‑month water‑use profile for the proposed cooling strategy, and to include the data in a slide deck for the county council.
