Dan Batrack, Chairman & CEOSteve Burdick, Executive VP & CFO

EARNINGS CALLQ3-20July 30, 2020

WATER ENVIRONMENT SUSTAINABLE INFRASTRUCTURE

Certain statements contained in this presentation are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These statements involve risks and uncertainties, such as those related to fluctuations in the Company’s quarterly operating results and stock price, and the other risks detailed from time to time in the Company’s SEC reports.

To supplement the financial results presented in accordance with generally accepted accounting principles in the United States (“GAAP”), we present certain non-GAAP financial measures within the meaning of Regulation G under the Securities Exchange Act of1934, as amended. We provide these non-GAAP financial measures because we believe they provide a valuable perspective on our financial results. However, non-GAAP measures have limitations as analytical tools and should not be considered in isolation and are not in accordance with, or a substitute for, GAAP measures. In addition, other companies may define non-GAAP measures differently which limits the ability of investors to compare non-GAAP measures of Tetra Tech to those used by our peer companies. A reconciliation of these non-GAAP financial measures to the most directly comparable GAAP financial measures is available at www.investor.tetratech.com.

Forward Looking Statements & Non-GAAP Financial Measures

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Q3-20 Results

Q3-20

Revenue $710M

Net Revenue $560M

EPS $0.83

Adjusted EPS $0.78

Backlog $3.07B

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Net Revenue by Customer (Q3-20)

Customer% of

Net Rev.Pro-forma

Y/Y*Comments

U.S. Federal 31% 0%• Federal IT up

• International development projects delayed

U.S. State and Local 14% +5%*• Water infrastructure up

• Operational technology up

U.S. Commercial 25% -7%• Discretionary industrial programs down

• Regulatory driven programs steady

International 30% +3%*• International government stable

• Commercial discretionary down

U.S. Federal

U.S. State & Local

U.S. Commercial

International

* Excludes disaster response and Canadian turnkey pipeline disposition.

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Performance by Segment (Q3-20)

SegmentPro-forma

Net Rev Y/Y*Adj. OI Margin Comments

GSG +3% 13.5%• Water advanced analytics and IT up

• International development projects delayed

CIG -5% 10.1%• Industrial down

• Renewable energy up

GSG

CIG

* Excludes disaster response and Canadian turnkey pipeline disposition.

Backlog (Q3-20)

0

500

1000

1500

2000

2500

3000

Q3-18 Q4-18 Q1-19 Q2-19 Q3-19 Q4-19 Q1-20 Q2-20 Q3-20

$2.44B

Funded and

Authorized Work

Significant AwardsContract Ceiling

Funded Value

U.S. DoD Assessment & Evaluation Contract

$300M $11M

Int’l Dev. Task Orders ― $160M

U.S. Air Force Environmental Services Contract

$90M ―

EPA Region 3 Emergency Response and Preparedness Services contract

$47M $5M

U.S. Navy Task Orders ― $40M

USACE A-E Design Services Contract $34M ―

U.S. Army Task Orders ― $19M

Montana Environmental Services Contract

$15M ―

USAID Development Activities, Colombia Contract

$14M ―

U.S. EPA Task Orders ― $13M

U.S. DOS A-E Services Contract $10M ―

Various Commercial ― $333M

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$3.07B

Federal Contract Capacity: >$18B

Financial Overview (GAAP)

Net Revenue ($ in millions)

Q3-20 Guidance

$540M-$560M

Q3-19 Q3-20

Revenue ($ in millions)

• Disaster response

• Canadian disposition

Q3-19 Q3-20

$826$710

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Operating Income ($ in millions)

Q3-19 Q3-20

CIG margin

up

$64

Diluted EPS

Q3-19 Q3-20

$0.88

Q3-20

Adjusted EPS

$0.78

$0.83$65

$623 $560

Q3-20 Reconciliation Summary($ in millions, except EPS)

Revenue Net Revenue Operating Income EPS

GAAP $710 $560 $64 $0.83

Non-core Equipment Disposition ― ― (5) (0.06)

Earn-outs ― ― 1 0.01

Adjusted $710 $560 $60 $0.78

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Cash Flow Overview

Cash Flow from Operations ($ in millions)

+72% YTD

+30% TTM

Q3-20Q3-19

$14

$111

Net Debt ($ in millions)

Net debt/EBITDA: 0.5x

$225$136

Q3-20Q3-19

DSO

10-day improvement

Y/Y

Q3-20Q3-19

8070

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Liquidity and Capital AllocationQ3-20

• $9.2M in dividends in Q3

• $21M buyback in Q3; $223M buyback capacity

• Technical Expertise

• Geographical Presence

• Client Expansion

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• Net Debt/EBITDA: 0.5x

• Cash: $142M

• Access to capital: Over $800M

Return to Shareholders

Liquidity &Leverage

TTM Cash From Operations:

$290M

Acquisitions

• Increase efficiency and accuracy by applying autonomous monitoring

Tetra Tech Experts Leverage Advanced Analytics Technology Resources

Commercial Clients

• Enable Water Treatment remote operations

• Rapidly deploy and process disaster recovery assessments

State and Local

• Advanced environmental predictive analysis and digital dashboards

Federal Agencies

Te

tra T

ech

De

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ech

no

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ies

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• Further expansion of artificial intelligence, machine learning, and operational technology

2019

• Further expands data analytics, system modernization, and cloud services

• Adds innovation lab for artificial intelligence, advanced analytics, and cybersecurity solutions

• Proprietary data visualization and environmental modeling software

2023

TARGET:$500M

2021

Estimate$300M

2020

$200M

2018$75M

2016$50M

• Expands water data management services

$125M

U.S. Federal Advanced Analytics Growth Strategy

Organic and acquisitive growth

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Guidance

Net Revenue Adjusted Diluted EPS

Q4-20 $560M - $600M $0.78 - $0.83

FY-20 $2.32B - $2.36B $3.13 - $3.18

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Assumptions FY-20

• Includes intangible amortization of $11 million or $0.16 per share

• 24% effective tax rate for Q4-20

• 55 million average diluted shares

• Excludes contributions from future acquisitions

• Solid Q3 results with near record backlog

• Strong balance sheet and access to capital

• Technically differentiated business model –Leading with Science®

• Well-positioned to address global challenges in water, environment and climate change

Summary

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Questions & Answers

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