Exhibit 21
| Subsidiaries of Tetra Tech, Inc. | ||
| NAME | JURISDICTION OF FORMATION | |
| Advanced Management Technology, Inc. | Virginia | |
| America's Schoolhouse Consulting Services, Inc. | New York | |
| American Environmental Group, Ltd. | Ohio | |
| ARD, Inc. | Vermont | |
| Ardaman & Associates, Inc. | Florida | |
| Arlington Power Consulting Limited | Nigeria | |
| BFP Consultants Pty Ltd | Australia | |
| BIOCNG, LLC | New York | |
| Bovell Freeman Holley (Pty) Ltd | South Africa | |
| BPR-Énergie Inc. | Quebec, Canada | |
| BPR Inc. | Quebec, Canada | |
| BPR-Infrastructure Inc. | Quebec, Canada | |
| BPR-Triax Inc. | Quebec, Canada | |
| Carson Group (AKL) Limited | New Zealand | |
| Carson Group Limited | New Zealand | |
| CICP Consultores Internacionales, LLC | Delaware | |
| Clifton Coney Group (NZ) Limited | New Zealand | |
| Coffey Afghanistan LLC | Afghanistan | |
| Coffey Afghanistan Pty Ltd | Australia | |
| Coffey Africas Holdings Pty Ltd | Australia | |
| Coffey Americas Holdings Pty Ltd | Australia | |
| Coffey Asia Limited | China (Hong Kong) | |
| Coffey Australia Holdings Pty Ltd | Australia | |
| Coffey Consultoria Servicios SpA | Chile | |
| Coffey Corporate Pty Ltd | Australia | |
| Coffey Environments Australia Pty Ltd | Australia | |
| Coffey Environments Pty Ltd | Australia | |
| Coffey Europe ME Holdings Pty Ltd | Australia | |
| Coffey Geotechnics Limited | United Kingdom | |
| Coffey Geotechnics Pty Ltd | Australia | |
| Coffey GTS Arabia LLC | Saudi Arabia | |
| Coffey Holding SDN BHD | Malaysia | |
| Coffey International (Africa) (Pty) Ltd | South Africa | |
| Coffey International Development Holdings Limited | United Kingdom | |
| Coffey International Development Limited | United Kingdom | |
| Coffey International Development Pty Ltd | Australia | |
| Coffey International Development (Middle East) Pty Ltd | Australia | |
| Coffey International Development Sp. Z.O.O. | Poland | |
| Coffey International, Inc. | Delaware | |
| Coffey International Incorporated | Philippines | |
| Coffey International Limited | Australia | |
| Coffey International NZ Limited | New Zealand | |
| Coffey LPM Pty Ltd | Australia | |
| Coffey (Malaysia) SDN BHD | Malaysia | |
| Coffey Mining Pty Ltd | Australia | |
| Coffey Myanmar Limited | Myanmar | |
| Coffey Natural Systems Pty Ltd | Australia | |
| Coffey Nigeria Ltd | Nigeria | |
| Coffey Philippines Inc | Philippines | |
| Coffey Projects (Africa) (Pty) Ltd | South Africa | |
| Coffey Projects (International) Ltd | British Virgin Islands | |
| Coffey Projects (Middle East) Ltd | Bailiwick of Jersey | |
| Coffey Projects (New Zealand) Limited | New Zealand | |
| Coffey Services Australia Pty Ltd | Australia | |
| Coffey Services No 2 Pty Ltd | Australia | |
| Coffey Services (NZ) Limited | New Zealand | |
| Coffey Services PNG Limited | Papua New Guinea | |
| Coffey Testing Pty Ltd | Australia | |
| Coffey Thailand Limited | Thailand | |
| Coffey UK Limited | United Kingdom | |
| Cornerstone Environmental Group, LLC | New York | |
| Cosentini Associates, Inc. | New York | |
| DASCEM Pty Ltd | Australia | |
| DCK-TTEC LLC | Delaware | |
| Development Company for Technical & Environmental Consultancy LLC | Iraq | |
| Delaney Crushed Stone Products, Inc. | New York | |
| Duncan Rhodes Construction Management (Pty) Ltd | South Africa | |
| Duncan Rhodes Procurement (Pty) Ltd | South Africa | |
| Eco Logical Australia Pty Ltd | Australia | |
| Farsands Solutions Pty Ltd | Australia | |
| Foothills Indemnity, Inc. | Hawaii | |
| Fundacion MSI Colombia | Colombia | |
| Geosciences Consulting (ME) Pty Ltd | Australia | |
| Glumac | California | |
| Glumac Limited, Inc. | Hong Kong | |
| Glumac (Shanghai) Architectural Design Consulting Co., Ltd. | China | |
| Golden Spike Resources, LLC | Delaware | |
| Golden State Brownfields, LLC | Delaware | |
| Hagler Bailly Pakistan (Private) Limited | Pakistan | |
| Hydro-Ops LLC | Delaware | |
| IJSI Liberia, LLC | Liberia | |
| INDUS Corporation | Virginia | |
| INDUS Enterprise Solutions Inc. | Delaware | |
| INDUS Secure Network Solutions, LLC | Virginia | |
| INDUS ESS LLC | Virginia | |
| Innogiciel Inc. | Quebec, Canada | |
| Integrated Justice Systems International, LLC | Delaware | |
| Inversiones Tetra Tech Chile Holding Limitada | Chile | |
| Inversiones Tetra Tech Chile Acquisition Limitada | Chile | |
| IP3 Afrique, LLC | Senegal | |
| IT Environmental (Australia) Pty Ltd | Australia | |
| KIFAYATE (SARLAU) | Morocco | |
| Kiggiak-EBA Consulting Ltd. | Northwest Territories, Canada | |
| Kitimaat - Tetratech General Partner Ltd. | British Columbia, Canada | |
| Kitimaat - Tetratech Limited Partnership | British Columbia, Canada | |
| MACSIS Pty Ltd | Australia | |
| Management Systems International Maroc S.A.R.L. | Morocco | |
| Management Systems International Georgia | Georgia | |
| Management Systems International, Inc. | District of Columbia | |
| Mansys International S de RL de CV | Mexico | |
| Metálica Consultores S.A. | Chile | |
| Mideast Construction LLC | Delaware | |
| MSI Egypt LLC | Egypt | |
| MSI for the development of competencies and management consultancy Ltd. | Kurdistan | |
| MSI Pakistan (Private) Limited | Pakistan | |
| Nehtruh-EBA Consulting Ltd. | Northwest Territories, Canada | |
| NELPCO Limited Partnership | Yukon, Canada | |
| NND EBA Land Protection Corp. | Yukon, Canada | |
| Park L Projects Ltd. | British Columbia, Canada | |
| Parkland Pipeline Contractors Ltd. | Alberta, Canada | |
| Parkland Pipeline Equipment Ltd. | Alberta, Canada | |
| Parkland Projects Ltd. | Saskatchewan, Canada | |
| PRO-telligent, LLC | Delaware | |
| PRO-telligent Global, LLC | Virginia | |
| PRO-telligent Global Limited, LLC | Kenya | |
| PRO-telligent Global (South) Limited | Malawi | |
| PRT-Liberia Incorporated | Liberia | |
| Proteus Engineers Pty Ltd. | Australia | |
| Rooney Engineering, Inc. | Colorado | |
| Secure Networx LLC | Virginia | |
| Sodat Inc. | Quebec, Canada | |
| Taheel Tetra Tech L.L.C. | Saudi Arabia | |
| Tetra Tech Alaska, L.L.C. | Alaska | |
| Tetra Tech AMT FZ LLC | Fujairah, UAE | |
| Tetra Tech ARD, Inc. S. de R.L. de C.V | Mexico | |
| Tetra Tech Australia Holding Pty Ltd. | Australia | |
| Tetra Tech Australia Pty Ltd | Australia | |
| Tetra Tech BAS, Inc. | California | |
| Tetra Tech (Beijing) Consultancy Company Limited | China | |
| Tetra Tech Canada Construction Inc. | Canada | |
| Tetra Tech Canada Holding Corporation | Canada | |
| Tetra Tech Canada Inc. | Canada | |
| Tetra Tech Cape Canaveral, LLC | Florida | |
| Tetra Tech CES, LLC | Washington | |
| Tetra Tech Coffey Consultoria e Servicos Ltda | Brazil | |
| Tetra Tech Coffey Holding LLC | Delaware | |
| Tetra Tech Coffey Holding Pty Limited | Australia | |
| Tetra Tech Colombia SAS | Colombia | |
| Tetra Tech Construction, Inc. | New York | |
| Tetra Tech Construction Craft Payroll LLC | New York | |
| Tetra Tech Construction National Payroll LLC | Delaware | |
| Tetra Tech Construction Oil & Gas Payroll, LLC | Delaware | |
| Tetra Tech Consultoria Ltda | Brazil | |
| Tetra Tech Contingency Constructors, LLC | Delaware | |
| Tetra Tech do Brasil Participacoes Ltda. | Brazil | |
| Tetra Tech EC, Inc. | Delaware | |
| Tetra Tech EMC, Inc. | California | |
| Tetra Tech Engenharia e Consultoria Ltda. | Brazil | |
| Tetra Tech ES, Inc. | Delaware | |
| Tetra Tech ES, Inc. S. de R.L. de C.V | Mexico | |
| Tetra Tech ES India Private Limited. | India | |
| Tetra Tech EU B.V. | Netherlands | |
| Tetra Tech Executive Services, Inc. | California | |
| Tetra Tech Expeditionary Operations, Inc. | Delaware | |
| Tetra Tech Facilities Construction, LLC | New Jersey | |
| Tetra Tech Holding LLC | Delaware | |
| Tetra Tech IC, Inc. | Alberta, Canada | |
| Tetra Tech IN Inc. | Quebec, Canada | |
| Tetra Tech India Limited | India | |
| Tetra Tech Industries Africa (pty) Ltd. | South Africa | |
| Tetra Tech Industries General Partner Inc. | Canada | |
| Tetra Tech International, Inc. | Delaware | |
| Tetra Tech International S.A.C. | Peru | |
| Tetra Tech MA, Inc. | Delaware | |
| Tetra Tech Management Consultancy LLC | Oman | |
| Tetra Tech New Martinsville, LLC | Delaware | |
| Tetra Tech MIMDU, LLC | Delaware | |
| Tetra Tech NZ Limited | New Zealand | |
| Tetra Tech QC Inc. | Quebec, Canada | |
| Tetra Tech QE Inc. | Quebec, Canada | |
| Tetra Tech QI Inc. | Quebec, Canada | |
| Tetra Tech RAC Craft, LLC | Delaware | |
| Tetra Tech TAS Inc. | Ontario, Canada | |
| Tetra Tech Technical Services, Inc. | Delaware | |
| Tetra Tech Tesoro, Inc. | Virginia | |
| Tetra Tech Utility Construction, Inc. | Delaware | |
| TTI Ring Industries Limited | Jamaica | |
| Wardrop (Ghana) Ltd. | Ghana | |
| Western Utility Cable, Inc. | Illinois | |
| Western Utility Central, Inc. | Illinois | |
| Western Utility Contractors, Inc. | Illinois | |
| Western Utility Electric, Inc. | Illinois | |
| Western Utility LLC | Delaware | |
| Whalen & Company, Inc. | Delaware | |
| Whalen Service Corps Inc. | Delaware | |
| 646696 NB Inc | Canada | |
| 646756 NB Inc. | Canada | |