# EDGAR Filing Document

**Accession Number:** 0000831641
**File Stem:** 0001104659-26-035179
**Filing Date:** 2026-3
**Character Count:** 9538
**Document Hash:** 7785f95240a21946db9d9ca421157f5b
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-26-035179.hdr.sgml**: 20260326

**ACCESSION NUMBER**: 0001104659-26-035179

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 13

**CONFORMED PERIOD OF REPORT**: 20260326

**ITEM INFORMATION**: Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers

**ITEM INFORMATION**: Other Events

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20260326

**DATE AS OF CHANGE**: 20260326

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** TETRA TECH INC
- **CENTRAL INDEX KEY:** 0000831641
- **STANDARD INDUSTRIAL CLASSIFICATION:** SERVICES-ENGINEERING SERVICES [8711]
- **ORGANIZATION NAME:** 07 Trade & Services
- **EIN:** 954148514
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 0927

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-19655
- **FILM NUMBER:** 26798086

**BUSINESS ADDRESS:**
- **STREET 1:** 3475 EAST FOOTHILL BOULEVARD
- **CITY:** PASADENA
- **STATE:** CA
- **ZIP:** 91107
- **BUSINESS PHONE:** 6263514664

**MAIL ADDRESS:**
- **STREET 1:** 3475 EAST FOOTHILL BOULEVARD
- **CITY:** PASADENA
- **STATE:** CA
- **ZIP:** 91107

?xml version='1.0' encoding='ASCII'?

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**WASHINGTON, D.C. 20549**

**FORM 8-K**

**CURRENT REPORT**

**Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934**

Date of Report (Date of earliest event reported):

**March 26, 2026**

**TETRA TECH, INC.**

(Exact name of registrant as specified in its charter)

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| | | |
|:---|:---|:---|
| **Delaware** | **0-19655** | **95-4148514** |
| (State or other jurisdiction<br> of incorporation) | (Commission<br> File Number) | (IRS Employer<br> Identification Number) |

---

**3475 East Foothill Boulevard** **, Pasadena, California 91107**

(Address of principal executive office, including zip code)

**(626) 351-4664**

(Registrant's telephone number, including area code)

**Not Applicable**

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

◻ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) <br>

◻ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) <br>

◻ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) <br>

◻ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

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| | | |
|:---|:---|:---|
| **Title of each class** | **Trading symbol(s)** | **Name of each exchange on which registered** |
| Common Stock, $0.01 par value | TTEK | The Nasdaq Stock Market LLC |

---

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging Growth Company ◻

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ◻

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| | |
|:---|:---|
| **Item 5.02.** | **Departure of Directors or Principal Officers; Election of Directors; Appointment of Principal Officers.** |

---

On March 26, 2026, Tetra Tech, Inc. (the "Company") announced that Eric W. Thornburg has been appointed to the Board of Directors of the Company (the "Board"), effective March 30, 2026, to serve until the next Annual Meeting of Stockholders or until his successor has been duly chosen and qualified. The Board will consist of eight members, including Mr. Thornburg, at that time. Mr. Thornburg will serve as a member of the Compensation Committee and Nominating and Corporate Governance Committee.

Mr. Thornburg, 65, most recently served as the Chief Executive Officer of H20 America (previously SJW Group) from 2017 to 2025 and Chair of the Board of Directors from 2018 to 2026. Prior to joining H20 America, he served as Chief Executive Officer of Connecticut Water Service from 2006 to 2017 and Chair of the Board of Directors from 2007 to 2017. Mr. Thornburg previously was Vice President of American Water Works Corporation from 2003 to 2006 and President of Missouri American Water from 2001 to 2003. He holds a B.A. degree in Biology and Business from Cornell University and an M.B.A. from Indiana Wesleyan University.

Mr. Thornburg will receive compensation for his service as a non-employee director in accordance with the Company's non-employee director compensation program. Under this program, he will receive (1) an annual retainer of $110,000; (2) $2,000 for each meeting attended, when the number of Board meetings during the year has exceeded eight; and (3) an annual long-term equity award with a grant date fair value of $175,000, consisting sixty percent of performance stock units and forty percent of restricted stock units, each pro-rated for the portion of time that he is expected to serve as a director of the Company before the next annual award.

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| | |
|:---|:---|
| **Item 8.01.** | **Other Events.** |

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On March 26, 2026, the Company issued a press release announcing the matters described in Item 5.02. A copy of the press release is attached as Exhibit 99.1 and is incorporated by reference herein.

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| | |
|:---|:---|
| **Item 9.01.** | **Financial Statements and Exhibits.** |

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(d) Exhibits

[99.1](tm269832d1_ex99-1.htm) [Press Release, dated March 26, 2026.](tm269832d1_ex99-1.htm) <br>104 Cover Page Interactive Data File (embedded within the Inline XBRL document)

**SIGNATURES**

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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| | | |
|:---|:---|:---|
|  | TETRA TECH, INC. | TETRA TECH, INC. |
| Date: March 26, 2026 | By: | /s/ Dan L. Batrack |
|  |  | Dan L. Batrack |
|  |  | Executive Chairman |

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## Exhibit 99.1

**Exhibit 99.1**

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| | |
|:---|:---|
| ![](tm269832d1_ex99-1img001.jpg) | ***NEWS RELEASE***<br> March 26, 2026 |

---

**Tetra Tech Appoints Eric W. Thornburg to its Board of Directors**

*Pasadena, California.* <u>Tetra Tech, Inc</u>. (NASDAQ: TTEK), a leading provider of high-end consulting and engineering services in water, environment, and sustainable infrastructure, announced today that Eric W. Thornburg, recently retired Chief Executive Officer of H20 America, has been appointed to the Company's Board of Directors, effective March 30, 2026. Mr. Thornburg will serve on the Compensation Committee and the Nominating and Corporate Governance Committee.

Mr. Thornburg brings more than 40 years of operational and strategic leadership in the water industry. He most recently served as Chair, President and CEO of H20 America (previously SJW Group), a network of local water and wastewater utilities serving more than 1.6 million people across the country. Prior to H20 America, Mr. Thornburg served as Chief Executive Officer of Connecticut Water Service.

"Eric brings deep leadership experience across diverse water utilities, with a track record of operational excellence, delivering growth and sustainable value to investors, and significant leadership team building and development," said Dan Batrack, Tetra Tech Executive Chairman. "His insight into critical and resilient water infrastructure will benefit our focus on the water market."

Mr. Thornburg began his career at American Water Works Corporation, developing expertise in all facets of water utility operations. He holds a B.A. degree in Biology and Business from Cornell University and an M.B.A. from Indiana Wesleyan University.

**About Tetra Tech**

<u>Tetra Tech</u> is the leader in water, environment and sustainable infrastructure, providing high-end consulting and engineering services for projects worldwide. With more than 25,000 employees working together, Tetra Tech provides clear solutions to complex problems by *Leading with Science<sup>®</sup>* to address the entire water cycle, protect and restore the environment, and design sustainable and resilient infrastructure. For more information about Tetra Tech, please visit <u>tetratech.com</u> or follow us on <u>LinkedIn</u> and <u>Facebook</u>.

CONTACTS:

Jim Wu, Investor Relations

Charlie MacPherson, Media & Public Relations

(626) 470-2844

*Any statements made in this release that are not based on historical fact are forward-looking statements. Any forward-looking statements made in this release represent management's best judgment as to what may occur in the future. However, Tetra Tech's actual outcome and results are not guaranteed and are subject to certain risks, uncertainties and assumptions ("Future Factors"), and may differ materially from what is expressed. For a description of Future Factors that could cause actual results to differ materially from such forward-looking statements, see the discussion under the section "Risk Factors" included in the Company's Form 10-K and Form 10-Q filings with the Securities and Exchange Commission.*