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Xylem's SonTek unit files notice to close San Diego site

Xylem's SonTek unit files notice to close San Diego site

Money Moves San Diego, CA local

Water measurement firm plans November shutdown affecting all 36 local employees

September 4th, 2026: SonTek files WARN notice

Overview

Updated 1 hour ago

SonTek, the San Diego maker of acoustic Doppler instruments that measure river flow and ocean currents, filed a California WARN notice Thursday to close its local site. The shutdown is dated November 6 and affects all 36 employees on staff.

SonTek came under Xylem through the water giant's 2012 purchase of YSI, which had owned SonTek since 2004. The closure fits a pattern: Xylem has been folding the instrument brands it accumulated through acquisition into fewer facilities.

Why it matters

The closure ends a 36-year San Diego maker of river and ocean current meters, signaling Xylem's consolidation of the brands it bought into fewer sites.

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Key Indicators

36
Employees affected
All SonTek San Diego staff face job loss in the shutdown.
63 days
Notice period
Days from the WARN filing (Sept 4) to the planned closure (Nov 6), exceeding the 60-day legal minimum.
100%
Share of site workforce laid off
The entire San Diego operation is set to shut down, not a partial reduction.

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People Involved

Organizations Involved

Timeline

January 1990 November 2026

5 events Latest: September 4th, 2026 · 1 week ago
Tap a bar to jump to that date
  1. Planned closure date

    Upcoming Milestone

    The San Diego facility shutdown is scheduled to take effect, ending SonTek's local run.

  2. SonTek files WARN notice

    Latest Regulatory Filing

    SonTek notifies California of its plan to close the San Diego site, affecting 36 employees.

  3. Xylem acquires YSI

    Acquisition

    Xylem completes its purchase of YSI, bringing SonTek under the Xylem umbrella.

  4. YSI acquires SonTek

    Acquisition

    YSI Inc. buys SonTek, folding the San Diego firm into its water monitoring portfolio.

  5. SonTek founded in San Diego

    Founding

    Engineers who left RD Instruments start an acoustic Doppler current profiler maker.

Scenarios

1

Xylem relocates SonTek production, keeps brand alive

Likely Resolves by Q2 2027

Discussed by: Water industry analysts and former SonTek staff

Xylem moves the remaining SonTek current profiler and flow product lines to another facility, likely its YSI site in Ohio or a Texas plant. The SonTek brand stays on the market, but the San Diego jobs end as scheduled on November 6.

2

SonTek brand phases out, products fold into Xylem Analytics

Possible Resolves by End of 2027

Discussed by: Instrument industry analysts

Xylem retires the SonTek name entirely. The acoustic Doppler product lines fold under Xylem's analytics portfolio, and the San Diego closure is the final step of that integration. Customers buy the same hardware under different branding.

3

Closure delayed or rescinded

Unlikely Resolves by Nov 6, 2026

Discussed by: Workforce and labor analysts

Part or all of the November shutdown is postponed, due to order backlogs, efforts to retain key engineers, or local pressure. A revised notice or withdrawal appears on the EDD WARN list before the closure date.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

2004

RD Instruments joins Teledyne (2004)

RD Instruments (RDI), SonTek's hometown rival in San Diego acoustic Doppler current profiling, was acquired by Teledyne Technologies. The two firms had competed for decades on ocean and river measurement hardware.

Then

RDI became part of Teledyne Marine, keeping its brand and San Diego-area base.

Now

The acoustic Doppler profiler market settled into two conglomerate-owned camps: Teledyne with RDI, and Xylem with SonTek.

Why this matters now

Shows how independent instrument makers that once competed in San Diego got absorbed by larger firms, setting the stage for consolidation decisions like the SonTek closure.

October 2011

ITT spins off Xylem (2011)

ITT Corporation split into three companies, with its water businesses becoming Xylem Inc., a pure-play water technology firm listed on the New York Stock Exchange.

Then

Xylem began life with a portfolio of inherited water brands and no legacy of its own manufacturing footprint.

Now

The structure gave Xylem a mandate to grow by acquisition and later rationalize brands, which is how it bought YSI and eventually closed the SonTek site.

Why this matters now

Explains why SonTek is owned by a consolidation-focused water conglomerate rather than operating as an independent San Diego firm.

2012

Xylem buys YSI, inherits SonTek (2012)

Xylem acquired YSI Inc., the Ohio-based water quality monitoring company that had owned SonTek since 2004. The deal brought SonTek's acoustic Doppler product line into Xylem's analytics group.

Then

SonTek became a smaller brand inside a much larger portfolio, with its San Diego site one of many Xylem facilities.

Now

The acquisition created the integration pressure that later surfaced as facility closures when Xylem sought cost savings.

Why this matters now

This is the mechanism that put SonTek under Xylem; the 2026 closure is the late-stage consequence of that 2012 integration.

Sources

(3)