Company lists · Data refreshed September 2026

Top 25 Environmental auditing firms based in the United States

Name: Environmental auditing 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 19, 2026 774 companies tracked

RevenueBase identified 774 environmental auditing firms headquartered in the United States as of September 2026 and tracks 11,463 professional contacts across them, including 5,732 with verified work emails. Houston is the largest hub.

This list covers environmental auditing 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 19, 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 19, 2026 86% judged on-target in blind review

774Companies

11,463Contacts tracked

5,732Verified emails

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The 25 largest environmental auditing firms based in the United States

Ranked by team size

Top 25 of 774 environmental auditing firms based in the United States, ranked by team size, largest first. Data refreshed Sep 19, 2026. RevenueBase Smart Search rates how each company's information relates to environmental auditing 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	Alliance Technical Group	Partial evidence	Decatur, AL, United StatesHQ checked Sep 19, 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 19, 2026
2	Rincon Consultants	Partial evidence	Ventura, CA, United StatesHQ checked Sep 19, 2026	501-1,000	479 contacts →
	Partial 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 19, 2026
3	Groundwater & Environmental Services, INC	Partial evidence	Wall Township, NJ, United StatesHQ checked Sep 19, 2026	201-500	447 contacts →
	Partial evidence “We are Groundwater & Environmental Services, Inc, better known as GES.” Source: RevenueBase Database · checked Sep 19, 2026
4	ROUX	Partial evidence	Islandia, NY, United StatesHQ checked Sep 19, 2026	201-500	433 contacts →
	Partial 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 19, 2026
5	Metiri Group	Partial evidence	Clovis, CA, United StatesHQ checked Sep 19, 2026	n/a	233 contacts →
	Partial evidence “Appl Inc is an environmental services company based out of 908 N Temperance Ave, Clovis, CA, United States.” Source: RevenueBase Database · checked Sep 19, 2026
6	August Mack Environmental, INC	Indirect evidence	Indianapolis, IN, United StatesHQ checked Sep 19, 2026	51-200	210 contacts →
	Indirect evidence Source: RevenueBase Database · checked Sep 19, 2026
7	Ecorp Consulting, INC	Indirect evidence	Rocklin, CA, United StatesHQ checked Sep 19, 2026	51-200	166 contacts →
	Indirect evidence Source: RevenueBase Database · checked Sep 19, 2026
8	Keramida INC	Indirect evidence	Indianapolis, IN, United StatesHQ checked Sep 19, 2026	51-200	152 contacts →
	Indirect evidence “Founded in 1988, KERAMIDA is a multidisciplinary Sustainability, EHS & Engineering consulting firm grounded in evidence-based research and development.” Source: RevenueBase Database · checked Sep 19, 2026
9	Quest Resource Management Group, A Qrhc Company Nasdaq Qrhc	Partial evidence	The Colony, TX, United StatesHQ checked Sep 19, 2026	51-200	147 contacts →
	Partial evidence “Quest Resource Management Group, a subsidiary of Quest Resource Holding Corporation (Nasdaq: QRHC), is a full-service environmental consulting and management company headquartered…” Source: RevenueBase Database · checked Sep 19, 2026
10	Mostardi Platt	Partial evidence	Elmhurst, IL, United StatesHQ checked Sep 19, 2026	51-200	140 contacts →
	Partial evidence “Since the passage of original environmental legislation nearly four decades ago, both private and public industry have turned to Mostardi Platt for guidance in complying with air…” Source: RevenueBase Database · checked Sep 19, 2026
11	Ensolum, LLC	Partial evidence	Dallas, TX, United StatesHQ checked Sep 19, 2026	51-200	136 contacts →
	Partial evidence “OUR MISSION is to combine sustainable environmental solutions with forward-thinking, cost-effective, innovative, and value-added technologies that balance our clients’ economic…” Source: RevenueBase Database · checked Sep 19, 2026
12	PPM Consultants, INC	Partial evidence	Birmingham Office, AL, United StatesHQ checked Sep 19, 2026	51-200	118 contacts →
	Partial evidence “PPM Consultants is an environmental and engineering consulting firm providing services to industrial, commercial, and governmental clients.” Source: RevenueBase Database · checked Sep 19, 2026
13	Edge Engineering And Science, LLC	Indirect evidence	Houston, TX, United StatesHQ checked Sep 19, 2026	51-200	116 contacts →
	Indirect evidence “Edge Engineering & Science, LLC (EDGE) is a privately owned professional services firm headquartered in Houston, Texas.” Source: RevenueBase Database · checked Sep 19, 2026
14	Farallon Consulting	Partial evidence	Bellevue, WA, United StatesHQ checked Sep 19, 2026	51-200	106 contacts →
	Partial evidence “Farallon Consulting helps clients navigate complex environmental challenges with practical, technically-sound solutions grounded in accuracy, integrity, and collaboration.” Source: RevenueBase Database · checked Sep 19, 2026
15	Techlaw	Partial evidence	Chantilly, VA, United StatesHQ checked Sep 19, 2026	201-500	104 contacts →
	Partial evidence “Established in 1983, TechLaw provides environmental and management consulting services to the public sector nationwide.” Source: RevenueBase Database · checked Sep 19, 2026
16	Hart & Hickman, PC	Partial evidence	Charlotte, NC, United StatesHQ checked Sep 19, 2026	51-200	103 contacts →
	Partial evidence “Hart & Hickman PC provides environmental consulting services to commercial, industrial, and governmental clients throughout the Southeast US.” Source: RevenueBase Database · checked Sep 19, 2026
17	Chambers Group, INC	Partial evidence	Costa Mesa, CA, United StatesHQ checked Sep 19, 2026	51-200	98 contacts →
	Partial evidence “Public agencies and businesses have been relying on Chambers Group to keep them in compliance with applicable federal, state, and/or local environmental laws, regulations, and…” Source: RevenueBase Database · checked Sep 19, 2026
18	A-Tech Consulting, INC	Indirect evidence	Orange, CA, United StatesHQ checked Sep 19, 2026	51-200	97 contacts →
	Indirect evidence Source: RevenueBase Database · checked Sep 19, 2026
19	AKT Peerless	Partial evidence	Saginaw, MI, United StatesHQ checked Sep 19, 2026	51-200	96 contacts →
	Partial evidence “We are environmental consultants and redevelopment experts who are proud to help build sustainable communities.” Source: RevenueBase Database · checked Sep 19, 2026
20	Aspen Environmental Group	Partial evidence	Agoura Hills, CA, United StatesHQ checked Sep 19, 2026	51-200	94 contacts →
	Partial evidence “Aspen Environmental Group is an expert interdisciplinary environmental impact analysis firm, specializing in the management of environmental assessment efforts under CEQA, NEPA…” Source: RevenueBase Database · checked Sep 19, 2026
21	Water & AIR Research, INC	Indirect evidence	Gainesville, FL, United StatesHQ checked Sep 19, 2026	11-50	87 contacts →
	Indirect evidence “Water and Air Research, Inc.” Source: RevenueBase Database · checked Sep 19, 2026
22	Eagle Certification Group	Partial evidence	Dayton, OH, United StatesHQ checked Sep 19, 2026	11-50	80 contacts →
	Partial evidence “Since 1994, EAGLE has built an excellent reputation by providing third party auditing services that are objective and value-added.” Source: RevenueBase Database · checked Sep 19, 2026
23	Cgrs INC	Indirect evidence	Fort Collins, CO, United StatesHQ checked Sep 19, 2026	51-200	70 contacts →
	Indirect evidence “We deliver quality solutions with integrity and expertise, every time.” Source: RevenueBase Database · checked Sep 19, 2026
24	Environmental Services, Inc., A Terracon Company	Partial evidence	Jacksonville, FL, United StatesHQ checked Sep 19, 2026	51-200	70 contacts →
	Partial evidence “Environmental Services, Inc.(ESI) is a leading full service environmental consulting firm with national and international experience.” Source: RevenueBase Database · checked Sep 19, 2026
25	Environmental Research Group, LLC ERG	Partial evidence	Baltimore, MD, United StatesHQ checked Sep 19, 2026	51-200	69 contacts →
	Partial evidence “We do environmental work.” Source: RevenueBase Database · checked Sep 19, 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 auditing 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 auditing firms.
Partial evidence: Its own public description names part of environmental auditing firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name environmental auditing 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 774 environmental auditing firms based in the United States

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Environmental auditing firms based in the United States at a glance

As of Sep 19, 2026

50.0%Verified-email coverage

14.8Average contacts per company

1-10Median size (employees)

3.6%Largest-city concentration · Houston

Sep 19, 2026Page data refreshed

Companies by employee count

1-10

419

11-50

276

51-200

201-500

501-1,000

1,001-5,000

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 774 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 auditing 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 auditing 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 auditing 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 auditing 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, 5,732 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 19, 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 auditing firms by metro

Environmental auditing firms in Houston28

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 auditing 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 auditing firms are there based in the United States?

RevenueBase identified 774 environmental auditing 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?

Alliance Technical Group, headquartered in Decatur, tops this list with the largest team on record.

Which city has the most environmental auditing firms?

Houston leads with 28 headquartered companies, followed by New York (11) and Tampa (11).

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 5,732 verified decision-maker contacts tracked across these 774 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 19, 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.