Company lists · Data refreshed September 2026

Top 25 Environmental engineering firms based in the United States

Name: Environmental engineering firms based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 16, 2026 6,932 companies tracked

RevenueBase identified 6,932 environmental engineering firms headquartered in the United States as of September 2026 and tracks 310,384 professional contacts across them, including 149,573 with verified work emails. Houston is the largest hub.

This list covers environmental engineering firms headquartered in the United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 16, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 16, 2026 86% judged on-target in blind review

6,932Companies

310,384Contacts tracked

149,573Verified emails

Explore this list → Free signup · no credit card · 500 free credits

The 25 largest environmental engineering firms based in the United States

Ranked by team size

Top 25 of 6,932 environmental engineering firms based in the United States, ranked by team size, largest first. Data refreshed Sep 16, 2026. RevenueBase Smart Search rates how each company's information relates to environmental engineering firms: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Tetra Tech	Strong evidence	Pasadena, CA, United StatesHQ checked Sep 16, 2026	10001+	12,999 contacts →
	Strong evidence “Tetra Tech is the leader in water, environment and sustainable infrastructure, providing high-end technical and engineering services for projects worldwide.” Source: RevenueBase Database · checked Sep 16, 2026
2	WSP In The U.S	Partial evidence	New York, NY, United StatesHQ checked Sep 16, 2026	10001+	9,318 contacts →
	Partial evidence “What if you could shape built and natural environments – and the future of those that use them?” Source: RevenueBase Database · checked Sep 16, 2026
3	Clean Harbors	Partial evidence	Norwell, MA, United StatesHQ checked Sep 16, 2026	10001+	8,924 contacts →
	Partial evidence “Clean Harbors is North America’s leading provider of environmental and industrial services.” Source: RevenueBase Database · checked Sep 16, 2026
4	CDM Smith	Partial evidence	Boston, MA, United StatesHQ checked Sep 16, 2026	5,001-10,000	7,527 contacts →
	Partial evidence “CDM Smith is shaping what’s next, now, with world class solutions in water, environment, transportation and energy to public and private clients worldwide.” Source: RevenueBase Database · checked Sep 16, 2026
5	Terracon	Partial evidence	Olathe, KS, United StatesHQ checked Sep 16, 2026	5,001-10,000	6,113 contacts →
	Partial evidence “Terracon is a 100 percent employee-owned consulting engineering firm providing quality services to clients.” Source: RevenueBase Database · checked Sep 16, 2026
6	Michael Baker International	Partial evidence	Pittsburgh, PA, United StatesHQ checked Sep 16, 2026	5,001-10,000	4,362 contacts →
	Partial evidence “Michael Baker International is a leading provider of engineering, consulting, and technology services spanning four Verticals: Infrastructure, Places and Facilities, Federal and…” Source: RevenueBase Database · checked Sep 16, 2026
7	APTIM	Partial evidence	Baton Rouge, LA, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,639 contacts →
	Partial evidence “APTIM enhances the quality of the environment, wellbeing of people, resilience of communities, and opportunity for employees to make a difference, not just a living.” Source: RevenueBase Database · checked Sep 16, 2026
8	Brown And Caldwell	Indirect evidence	Walnut Creek, CA, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,473 contacts →
	Indirect evidence “Headquartered in Walnut Creek, Calif, Brown and Caldwell is an employee-owned firm with 2,100+ professionals serving clients locally and globally from 52 locations.” Source: RevenueBase Database · checked Sep 16, 2026
9	Geosyntec Consultants	Strong evidence	Boca Raton, FL, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,393 contacts →
	Strong evidence “Geosyntec is a consulting and engineering firm that works with private and public sector clients to address new ventures and complex problems involving our environment, natural…” Source: RevenueBase Database · checked Sep 16, 2026
10	Providence	Strong evidence	Baton Rouge, LA, United StatesHQ checked Sep 16, 2026	n/a	2,232 contacts →
	Strong evidence “Providence is an employee-owned engineering and environmental consulting firm.” Source: RevenueBase Database · checked Sep 16, 2026
11	ECS Group Of Companies	Partial evidence	Chantilly, VA, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,210 contacts →
	Partial evidence “ECS Group of Companies is a Chantilly, VA-based consulting engineering firm.” Source: RevenueBase Database · checked Sep 16, 2026
12	KCI	Partial evidence	Sparks, NC, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,207 contacts →
	Partial evidence “KCI is a 100-percent employee-owned engineering, consulting and construction firm serving clients throughout the United States and beyond.” Source: RevenueBase Database · checked Sep 16, 2026
13	Langan Engineering & Environmental Services	Partial evidence	Parsippany, NJ, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,177 contacts →
	Partial evidence “Langan's client-focused, highly entrepreneurial culture cultivates an environment of opportunities in which career growth and teamwork flourish.” Source: RevenueBase Database · checked Sep 16, 2026
14	Civil & Environmental Consultants, INC	Partial evidence	Moon Township, PA, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,145 contacts →
	Partial evidence “Civil & Environmental Consultants, Inc.(CEC) provides comprehensive market-oriented consulting services that advance the strategic business objectives of its clients.” Source: RevenueBase Database · checked Sep 16, 2026
15	Olsson	Partial evidence	Lincoln, NE, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,108 contacts →
	Partial evidence “Olsson is an engineering firm made up of people who craft expert solutions and designs that improve communities.” Source: RevenueBase Database · checked Sep 16, 2026
16	Hazen And Sawyer	Indirect evidence	New York, NY, United StatesHQ checked Sep 16, 2026	1,001-5,000	2,100 contacts →
	Indirect evidence “As Hazen marks 75 years, we celebrate a legacy of absolute commitment to our clients while delivering the best technical work available anywhere.” Source: RevenueBase Database · checked Sep 16, 2026
17	IMEG	Partial evidence	Rock Island, IL, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,985 contacts →
	Partial evidence “Leaders in Engineering and Innovation.” Source: RevenueBase Database · checked Sep 16, 2026
18	LJA	Indirect evidence	Houston, TX, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,932 contacts →
	Indirect evidence “Employee-Owned.” Source: RevenueBase Database · checked Sep 16, 2026
19	Carollo Engineers	Indirect evidence	Walnut Creek, CA, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,718 contacts →
	Indirect evidence “For more than 90 years, Carollo Engineers has been dedicated exclusively to water and wastewater solutions.” Source: RevenueBase Database · checked Sep 16, 2026
20	Bowman Consulting	Partial evidence	Reston, VA, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,666 contacts →
	Partial evidence “Headquartered in Reston, Virginia, Bowman is a national engineering services firm delivering infrastructure solutions to customers who own, develop and maintain the built…” Source: RevenueBase Database · checked Sep 16, 2026
21	Rk&k	Strong evidence	Baltimore, MD, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,641 contacts →
	Strong evidence “RK & K is a full-service planning, engineering, environmental, and construction management/inspection firm serving a wide range of clients throughout the United States.” Source: RevenueBase Database · checked Sep 16, 2026
22	CHA Consulting, INC	Partial evidence	Albany, NY, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,639 contacts →
	Partial evidence “CHA Consulting, Inc.(CHA) is an innovative, full-service engineering, design, consulting, and program/construction management firm providing a wide range of technology-enhanced…” Source: RevenueBase Database · checked Sep 16, 2026
23	Swca Environmental Consultants	Partial evidence	Phoenix, AZ, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,629 contacts →
	Partial evidence “Founded on a commitment to sound science and creative solutions, SWCA is a leader in environmental and management consulting services.” Source: RevenueBase Database · checked Sep 16, 2026
24	GEI Consultants, INC	Indirect evidence	Woburn, MA, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,604 contacts →
	Indirect evidence Source: RevenueBase Database · checked Sep 16, 2026
25	UES	Strong evidence	Orlando, FL, United StatesHQ checked Sep 16, 2026	1,001-5,000	1,595 contacts →
	Strong evidence “UES provides professional engineering, environmental, testing and inspection services to clients across the United States.” Source: RevenueBase Database · checked Sep 16, 2026

RevenueBase Smart Search

RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: environmental engineering firms. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.

Strong evidence: The company's own public description of its business names environmental engineering firms.
Partial evidence: Its own public description names part of environmental engineering firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name environmental engineering firms. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.

RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.

Showing 25 of 6,932 environmental engineering firms based in the United States

See the full list, filter by size, metro and specialty, and get verified emails and direct dials for all 149,573 reachable decision-makers.

Free signup · no credit card

View the full list →

Environmental engineering firms based in the United States at a glance

As of Sep 16, 2026

48.2%Verified-email coverage

44.8Average contacts per company

11-50Median size (employees)

2.0%Largest-city concentration · Houston

Sep 16, 2026Page data refreshed

Companies by employee count

1-10

2,943

11-50

2,642

51-200

940

201-500

227

501-1,000

1,001-5,000

5,001-10,000

10001+

Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 6,932 companies.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among environmental engineering firms, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
What qualifies: Companies headquartered in the United States whose own description of what they do matches “environmental engineering firms”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search: RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names environmental engineering firms), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude: Companies whose own description does not clearly place them among environmental engineering firms, and records with no verified work email. Companies headquartered outside United States are excluded even when they keep an office there.
Match quality: In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking: Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification: Every listed company carries at least one verified work email, 149,573 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh: This page's figures were pulled from the company graph on September 16, 2026. Lists refresh periodically as the graph is re-checked.
Corrections: Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Environmental engineering firms by metro

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names environmental engineering firms, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many environmental engineering firms are there based in the United States?

RevenueBase identified 6,932 environmental engineering firms headquartered in the United States as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

Tetra Tech, headquartered in Pasadena, tops this list with the largest team on record.

Which city has the most environmental engineering firms?

Houston leads with 138 headquartered companies, followed by New York (101) and Austin (73).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 149,573 verified decision-maker contacts tracked across these 6,932 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 16, 2026.

Ready to reach these companies? Verified emails and direct dials for all 6,932 environmental engineering firms based in the United States. Start with a free account, no credit card.

Download this list →

Related lists

Environmental engineering firms by geography

Browse the directory

Browse: Companies home · All United States lists · All Environmental engineering firms lists · New lists

About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.