| CHEN-NORTHERN, INC., Dissolved September 22, 2006Location not reported, CO · Voluntarily Dissolved | Location not reported, CO | Corporation | Mar 31, 1994 | Voluntarily Dissolved |
| PHARMACY SUPPORT CORPORATION, Dissolved August 1, 1999Location not reported, CO · Administratively Dissolved | Location not reported, CO | Corporation | Oct 11, 1994 | Administratively Dissolved |
| MAXIM TECHNOLOGIES, INC., Colorado Authority Terminated April 1, 2004Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Mar 18, 1996 | Withdrawn |
| ASERETH MEDICAL SERVICES, INC., Colorado Authority Terminated November 1, 2002Location not reported, CO · Revoked | Location not reported, CO | Corporation | May 24, 1996 | Revoked |
| ARMORED TRANSPORT, INC., Colorado Authority Terminated March 8, 2000Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Jun 4, 1996 | Withdrawn |
| KCM CONSTRUCTION MANAGEMENT & INSPECTION, INC.Location not reported, CO · Merged | Location not reported, CO | Corporation | Aug 28, 1996 | Merged |
| TETRA TECH NUS, INC., Colorado Authority Relinquished January 19, 2012Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Jan 13, 1998 | Withdrawn |
| LAL CORP., Colorado Authority Relinquished June 5, 2023Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Jun 18, 1998 | Withdrawn |
| WHALEN/SENTREX LLC, Colorado Authority Relinquished September 21, 2006Location not reported, CO · Withdrawn | Location not reported, CO | LLC | Sep 1, 1998 | Withdrawn |
| INTEGRATION TECHNOLOGIES, INC.Location not reported, CO · Merged | Location not reported, CO | Corporation | Dec 23, 1998 | Merged |
| WHALEN & COMPANY SERVICE CORPORATION, Colorado Authority Relinquished January 23, 2006Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Feb 1, 1999 | Withdrawn |
| TETRA TECH TECHNICAL SERVICES, INC.Location not reported, CO · Good Standing | Location not reported, CO | Corporation | Apr 26, 1999 | Good Standing |
| Tetra Tech MM, Inc., Colorado Authority Relinquished January 9, 2008Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Jun 25, 1999 | Withdrawn |
| ENGINEERED COMMUNICATIONS, INC, Colorado Authority Terminated December 24, 2002Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Jun 30, 2000 | Withdrawn |
| TETRA TECH RMC, INC., Colorado Authority Relinquished January 9, 2009Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Dec 29, 2000 | Withdrawn |
| TETRA TECH EXECUTIVE SERVICES, INC.Location not reported, CO · Good Standing | Location not reported, CO | Corporation | Feb 8, 2001 | Good Standing |
| UTILITIES & C.C., INC.Location not reported, CO · Merged | Location not reported, CO | Corporation | Apr 3, 2001 | Merged |
| VERTEX ENGINEERING SERVICES, INC., Colorado Authority Relinquished January 10, 2006Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | May 25, 2001 | Withdrawn |
| M-S CASH DRAWER CORPORATION, Colorado Authority Terminated April 17, 2003Location not reported, CO · Revoked | Location not reported, CO | Corporation | Oct 11, 2001 | Revoked |
| SYSTINE INC., Colorado Authority Terminated December 23, 2002Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Oct 22, 2001 | Withdrawn |
| TETRA TECH LEASING, LLC, Colorado Authority Relinquished August 9, 2007Location not reported, CO · Withdrawn | Location not reported, CO | LLC | Oct 26, 2001 | Withdrawn |
| YOUNGKING GROUP, INC., Colorado Authority Terminated October 3, 2003Location not reported, CO · Revoked | Location not reported, CO | Corporation | Apr 8, 2002 | Revoked |
| SPARKLETTS WATERS OF NORTH AMERICA, LP, Colorado Authority Terminated April 15, 2004Location not reported, CO · Withdrawn | Location not reported, CO | Partnership | Aug 2, 2002 | Withdrawn |
| PACIFIC BANK TECHNOLOGY, INC., Colorado Authority Terminated May 3, 2004Location not reported, CO · Revoked | Location not reported, CO | Corporation | Nov 13, 2002 | Revoked |
| CHU & ASSOCIATES, INC., Colorado Authority Relinquished June 7, 2022Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Dec 12, 2002 | Withdrawn |
| Tetra Tech EC, Inc.Location not reported, CO · Good Standing | Location not reported, CO | Corporation | Feb 20, 2003 | Good Standing |
| BLUE HILLS DEVELOPMENT LLC, Colorado Authority Terminated October 31, 2004Location not reported, CO · Revoked | Location not reported, CO | LLC | May 15, 2003 | Revoked |
| RIJICHO OF THE SHINJI SHUMEKAI OF AMERICA, A CORPORATION SOLELocation not reported, CO · Good Standing | Location not reported, CO | Nonprofit | Jul 8, 2003 | Good Standing |
| Two Ply, L.P., Colorado Authority Relinquished December 22, 2006Location not reported, CO · Withdrawn | Location not reported, CO | Partnership | Dec 8, 2003 | Withdrawn |
| ADVANCED MANAGEMENT TECHNOLOGY, INC.Location not reported, CO · Good Standing | Location not reported, CO | Corporation | Feb 23, 2004 | Good Standing |
| HS COLORADO, LLCLocation not reported, CO · Good Standing | Location not reported, CO | LLC | May 19, 2004 | Good Standing |
| Arlan Sanchez Ministries, Inc.Location not reported, CO · Good Standing | Location not reported, CO | Nonprofit | Jul 28, 2004 | Good Standing |
| New Covenant House, Inc.Location not reported, CO · Good Standing | Location not reported, CO | Nonprofit | Jul 28, 2004 | Good Standing |
| HS Colorado II, LLCLocation not reported, CO · Good Standing | Location not reported, CO | LLC | Sep 14, 2004 | Good Standing |
| TETRA TECH BAS, INC.Location not reported, CO · Good Standing | Location not reported, CO | Corporation | Oct 22, 2004 | Good Standing |
| TETRA TECH ES, INC., Colorado Authority Relinquished February 12, 2020Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Dec 8, 2004 | Withdrawn |
| KCM, Inc., Colorado Authority Relinquished January 4, 2008Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Apr 13, 2005 | Withdrawn |
| HS Ohio, LLCLocation not reported, CO · Good Standing | Location not reported, CO | LLC | Aug 25, 2005 | Good Standing |
| Tetra Tech EMC, Inc., Colorado Authority Relinquished October 17, 2019Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Sep 20, 2006 | Withdrawn |
| Harrington Group, CPAs, LLP, Delinquent December 1, 2023Location not reported, CO · Delinquent | Location not reported, CO | Partnership | Oct 11, 2006 | Delinquent |
| Whalen & Company, Inc., Colorado Authority Relinquished September 25, 2019Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Jun 27, 2007 | Withdrawn |
| Tetra Tech Acquisition, Inc.Location not reported, CO · Merged | Location not reported, CO | Corporation | Jun 24, 2008 | Merged |
| Tetra Tech Construction, Inc., Colorado Authority Relinquished December 5, 2017Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Mar 31, 2009 | Withdrawn |
| Gemalto Cogent, Inc., Colorado Authority Relinquished December 10, 2020Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | May 20, 2011 | Withdrawn |
| Acorn 4 Summit Blvd Real Estate, LLC, Dissolved October 10, 2014Location not reported, CO · Voluntarily Dissolved | Location not reported, CO | LLC | Apr 18, 2012 | Voluntarily Dissolved |
| Pro-telligent, LLC, Colorado Authority Relinquished May 18, 2017Location not reported, CO · Withdrawn | Location not reported, CO | LLC | Mar 20, 2013 | Withdrawn |
| Pueblo West Leasing, LLC, Colorado Authority Relinquished February 12, 2020Location not reported, CO · Withdrawn | Location not reported, CO | LLC | Jun 20, 2013 | Withdrawn |
| Lafayette Leasing, LLC, Colorado Authority Relinquished August 22, 2023Location not reported, CO · Withdrawn | Location not reported, CO | LLC | Jun 20, 2013 | Withdrawn |
| Bolton & Company, Colorado Authority Relinquished March 28, 2025Location not reported, CO · Withdrawn | Location not reported, CO | Corporation | Sep 19, 2013 | Withdrawn |
| Tetra Tech CEA, LLC, Colorado Authority Relinquished September 16, 2015Location not reported, CO · Withdrawn | Location not reported, CO | LLC | Sep 27, 2013 | Withdrawn |