Company lists · Data refreshed September 2026

Top 25 Environmental audit consulting firms based in the United States

Name: Environmental audit consulting 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 28, 2026 3,020 companies tracked

RevenueBase identified 3,020 environmental audit consulting firms headquartered in the United States as of September 2026 and tracks 67,711 professional contacts across them, including 29,172 with verified work emails. Houston is the largest hub.

This list covers environmental audit consulting 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 28, 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 28, 2026 86% judged on-target in blind review

3,020Companies

67,711Contacts tracked

29,172Verified emails

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The 25 largest environmental audit consulting firms based in the United States

Ranked by team size

Top 25 of 3,020 environmental audit consulting firms based in the United States, ranked by team size, largest first. Data refreshed Sep 28, 2026. RevenueBase Smart Search rates how each company's information relates to environmental audit consulting 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	APTIM	Partial evidence	Baton Rouge, LA, United StatesHQ checked Sep 28, 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 28, 2026
2	Civil & Environmental Consultants, INC	Strong evidence	Moon Township, PA, United StatesHQ checked Sep 28, 2026	1,001-5,000	2,145 contacts →
	Strong 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 28, 2026
3	Swca Environmental Consultants	Strong evidence	Phoenix, AZ, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,629 contacts →
	Strong 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 28, 2026
4	Montrose Environmental Group	Partial evidence	Little Rock, AR, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,529 contacts →
	Partial evidence “Onterris (formerly Montrose Environmental Group) was one of the first to see environmental responsibility as not just an imperative but as a strategic asset.” Source: RevenueBase Database · checked Sep 28, 2026
5	Sphera	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,349 contacts →
	Indirect evidence “Sphera creates a safer, more sustainable and productive world.” Source: RevenueBase Database · checked Sep 28, 2026
6	Adec Innovations	Indirect evidence	Irvine, CA, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,304 contacts →
	Indirect evidence “ADEC Innovations seamlessly delivers fully integrated, cost-effective industry expertise, business process & data management, and software services.” Source: RevenueBase Database · checked Sep 28, 2026
7	Apex Companies	Indirect evidence	Rockville, MD, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,137 contacts →
	Indirect evidence “Who is Apex?” Source: RevenueBase Database · checked Sep 28, 2026
8	Barr Engineering CO	Strong evidence	Minneapolis, MN, United StatesHQ checked Sep 28, 2026	1,001-5,000	1,088 contacts →
	Strong evidence “Barr provides engineering and environmental consulting services to clients across the Midwest, throughout the Americas, and around the world.” Source: RevenueBase Database · checked Sep 28, 2026
9	IEA	Strong evidence	Brooklyn Park, MN, United StatesHQ checked Sep 28, 2026	n/a	982 contacts →
	Strong evidence “The Institute for Environmental Assessment, Inc.(IEA) is small business committed to providing trusted environmental safety consulting services for private and public…” Source: RevenueBase Database · checked Sep 28, 2026
10	Trinity Consultants	Partial evidence	Dallas, TX, United StatesHQ checked Sep 28, 2026	1,001-5,000	961 contacts →
	Partial evidence “Trinity Consultants is a global team of experts helping organizations solve complex challenges in environmental compliance, ecological protection, infrastructure performance, and…” Source: RevenueBase Database · checked Sep 28, 2026
11	Alliance Technical Group	Partial evidence	Decatur, AL, United StatesHQ checked Sep 28, 2026	1,001-5,000	956 contacts →
	Partial evidence “Alliance is a new kind of environmental services company-powered by innovation, focused on service, and committed to client success.” Source: RevenueBase Database · checked Sep 28, 2026
12	ATC Group Services LLC	Indirect evidence	Lafayette, LA, United StatesHQ checked Sep 28, 2026	1,001-5,000	865 contacts →
	Indirect evidence “ATC Group Services LLC is now Atlas.” Source: RevenueBase Database · checked Sep 28, 2026
13	Environmental Science Associates	Strong evidence	San Francisco, CA, United StatesHQ checked Sep 28, 2026	501-1,000	732 contacts →
	Strong evidence “ESA is a 100% employee-owned environmental consulting firm.” Source: RevenueBase Database · checked Sep 28, 2026
14	Antea Group USA	Strong evidence	St Paul, MN, United StatesHQ checked Sep 28, 2026	1,001-5,000	658 contacts →
	Strong evidence “Antea Group is an international engineering and environmental consulting firm specializing in full-service solutions in the fields of environment, health and safety, and…” Source: RevenueBase Database · checked Sep 28, 2026
15	Trihydro Corporation	Strong evidence	Laramie, WY, United StatesHQ checked Sep 28, 2026	501-1,000	577 contacts →
	Strong evidence “Headquartered in Laramie, Wyoming, Trihydro provides environmental consulting, engineering and surveying, air quality and process management, information technology, and water and…” Source: RevenueBase Database · checked Sep 28, 2026
16	EBI Consulting	Indirect evidence	Burlington, MA, United StatesHQ checked Sep 28, 2026	501-1,000	535 contacts →
	Indirect evidence “For 35 years we have been helping investors, lenders, owners, developers, contractors, and property managers reduce risk and optimize their built facilities, infrastructure and…” Source: RevenueBase Database · checked Sep 28, 2026
17	Nova Engineering And Environmental, LLC	Strong evidence	Kennesaw, GA, United StatesHQ checked Sep 28, 2026	501-1,000	518 contacts →
	Strong evidence “Established in 1996, NOVA was originally founded to provide Environmental Consulting, Geotechnical Engineering, and Construction Materials Testing and Inspection services to the…” Source: RevenueBase Database · checked Sep 28, 2026
18	Rincon Consultants	Strong evidence	Ventura, CA, United StatesHQ checked Sep 28, 2026	501-1,000	479 contacts →
	Strong evidence “Rincon Consultants is a multi-disciplinary environmental sciences, planning, and engineering consulting firm that provides quality professional services to government and industry.” Source: RevenueBase Database · checked Sep 28, 2026
19	Enhesa	Indirect evidence	Arlington, VA, United StatesHQ checked Sep 28, 2026	201-500	474 contacts →
	Indirect evidence “At Enhesa we empower the world’s largest businesses to achieve compliance, manage risk, and drive sustainability with clear, actionable insights.” Source: RevenueBase Database · checked Sep 28, 2026
20	Groundwater & Environmental Services, INC	Partial evidence	Wall Township, NJ, United StatesHQ checked Sep 28, 2026	201-500	447 contacts →
	Partial evidence “We are Groundwater & Environmental Services, Inc, better known as GES.” Source: RevenueBase Database · checked Sep 28, 2026
21	ROUX	Strong evidence	Islandia, NY, United StatesHQ checked Sep 28, 2026	201-500	433 contacts →
	Strong evidence “Founded 40 years ago, Roux is recognized for being a highly effective, client-focused environmental consulting and management firm.” Source: RevenueBase Database · checked Sep 28, 2026
22	Western Ecosystems Technology, Inc. West	Strong evidence	Cheyenne, WY, United StatesHQ checked Sep 28, 2026	201-500	408 contacts →
	Strong evidence “WEST provides environmental and statistical consulting services and contract research nationally and internationally to industry, government, and private organizations.” Source: RevenueBase Database · checked Sep 28, 2026
23	P2s	Indirect evidence	Long Beach, CA, United StatesHQ checked Sep 28, 2026	201-500	375 contacts →
	Indirect evidence “P2S has brought forward-thinking, sustainable engineering solutions to California, the Pacific Northwest, and beyond, for over 30 years.” Source: RevenueBase Database · checked Sep 28, 2026
24	CME Associates	Partial evidence	Parlin, NJ, United StatesHQ checked Sep 28, 2026	201-500	336 contacts →
	Partial evidence “CME Associates, with eight (8) office locations throughout New Jersey, provides a complete range of Environmental, Geotechnical, Engineering, Surveying and Planning services.” Source: RevenueBase Database · checked Sep 28, 2026
25	LSA	Strong evidence	Irvine, CA, United StatesHQ checked Sep 28, 2026	201-500	332 contacts →
	Strong evidence “LSA is a diversified environmental, transportation, and community planning firm that evolved from a small consulting firm.” Source: RevenueBase Database · checked Sep 28, 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 audit consulting 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 audit consulting firms.
Partial evidence: Its own public description names part of environmental audit consulting firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name environmental audit consulting 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 3,020 environmental audit consulting firms based in the United States

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Environmental audit consulting firms based in the United States at a glance

As of Sep 28, 2026

43.1%Verified-email coverage

22.4Average contacts per company

1-10Median size (employees)

2.5%Largest-city concentration · Houston

Sep 28, 2026Page data refreshed

Companies by employee count

1-10

1,726

11-50

973

51-200

231

201-500

501-1,000

1,001-5,000

5,001-10,000

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 3,020 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 audit consulting 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 audit consulting 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 audit consulting 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 audit consulting 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, 29,172 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 28, 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 audit consulting 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 audit consulting 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 audit consulting firms are there based in the United States?

RevenueBase identified 3,020 environmental audit consulting 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?

APTIM, headquartered in Baton Rouge, tops this list with the largest team on record.

Which city has the most environmental audit consulting firms?

Houston leads with 74 headquartered companies, followed by New York (47) and Chicago (35).

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 29,172 verified decision-maker contacts tracked across these 3,020 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 28, 2026.

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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.