Company lists · Data refreshed September 2026

Top 25 Environmental compliance firms based in the United States

Name: Environmental compliance 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 2,372 companies tracked

RevenueBase identified 2,372 environmental compliance firms headquartered in the United States as of September 2026 and tracks 38,515 professional contacts across them, including 18,230 with verified work emails. Houston is the largest hub.

This list covers environmental compliance 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

2,372Companies

38,515Contacts tracked

18,230Verified emails

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The 25 largest environmental compliance firms based in the United States

Ranked by team size

Top 25 of 2,372 environmental compliance 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 compliance 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	Montrose Environmental Group	Partial evidence	Little Rock, AR, United StatesHQ checked Sep 19, 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 19, 2026
2	Trinity Consultants	Strong evidence	Dallas, TX, United StatesHQ checked Sep 19, 2026	1,001-5,000	961 contacts →
	Strong 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 19, 2026
3	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
4	CT Corporation	Partial evidence	New York, NY, United StatesHQ checked Sep 19, 2026	1,001-5,000	788 contacts →
	Partial evidence “CT Corporation helps small businesses, corporations, and law firms around the world manage their most critical business and legal compliance responsibilities.” Source: RevenueBase Database · checked Sep 19, 2026
5	Environmental Science Associates	Partial evidence	San Francisco, CA, United StatesHQ checked Sep 19, 2026	501-1,000	732 contacts →
	Partial evidence “ESA is a 100% employee-owned environmental consulting firm.” Source: RevenueBase Database · checked Sep 19, 2026
6	Antea Group USA	Partial evidence	St Paul, MN, United StatesHQ checked Sep 19, 2026	1,001-5,000	658 contacts →
	Partial 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 19, 2026
7	VLS Environmental Solutions, LLC	Partial evidence	Houston, TX, United StatesHQ checked Sep 19, 2026	1,001-5,000	481 contacts →
	Partial evidence “At VLS, we address your company’s most significant hurdles with waste management and compliance through sustainable solutions.” Source: RevenueBase Database · checked Sep 19, 2026
8	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
9	Enhesa	Partial evidence	Arlington, VA, United StatesHQ checked Sep 19, 2026	201-500	474 contacts →
	Partial 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 19, 2026
10	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
11	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
12	GSI Environmental INC	Partial evidence	Houston, TX, United StatesHQ checked Sep 19, 2026	201-500	259 contacts →
	Partial evidence “GSI Environmental, Inc.(GSI), is an environmental engineering and science consulting firm committed to measuring, analyzing, and solving complex environmental problems around the…” Source: RevenueBase Database · checked Sep 19, 2026
13	Alliance Environmental Group, LLC	Partial evidence	Azusa, CA, United StatesHQ checked Sep 19, 2026	501-1,000	254 contacts →
	Partial evidence “Alliance is one of the most experienced and trusted environmental contractors in California.” Source: RevenueBase Database · checked Sep 19, 2026
14	Environmental Works, INC	Partial evidence	Springfield, MO, United StatesHQ checked Sep 19, 2026	201-500	238 contacts →
	Partial evidence “Environmental Works, Inc.(EWI) offers truly comprehensive environmental solutions for a variety of industries, businesses, and municipalities.” Source: RevenueBase Database · checked Sep 19, 2026
15	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
16	Tanknology	Strong evidence	Austin, TX, United StatesHQ checked Sep 19, 2026	201-500	232 contacts →
	Strong evidence “Tanknology is the world's largest provider of tank testing and environmental compliance services for petroleum systems.” Source: RevenueBase Database · checked Sep 19, 2026
17	Patriot Environmental Services	Partial evidence	Signal Hill, CA, United StatesHQ checked Sep 19, 2026	201-500	223 contacts →
	Partial evidence “Patriot Environmental Services, a Crystal Clean company, is a leading environmental service provider with clients throughout the Southwestern United States.” Source: RevenueBase Database · checked Sep 19, 2026
18	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
19	Hillmann Consulting, LLC	Partial evidence	Union, NJ, United StatesHQ checked Sep 19, 2026	201-500	209 contacts →
	Partial evidence “Hillmann has been a well-recognized leader in the Environmental Health & Safety, Due Diligence & Remediation Management, and Construction Services industries since 1985.” Source: RevenueBase Database · checked Sep 19, 2026
20	Helix Environmental Planning, INC	Partial evidence	La Mesa, CA, United StatesHQ checked Sep 19, 2026	201-500	199 contacts →
	Partial evidence “HELIX Environmental Planning, Inc.(HELIX) is an employee-owned, environmental consulting firm established in 1991 and with offices in San Diego, Los Angeles, Orange, Riverside…” Source: RevenueBase Database · checked Sep 19, 2026
21	Normandeau Associates, INC	Indirect evidence	Bedford, NH, United StatesHQ checked Sep 19, 2026	201-500	189 contacts →
	Indirect evidence Source: RevenueBase Database · checked Sep 19, 2026
22	Enviroscience, INC	Partial evidence	Stow, OH, United StatesHQ checked Sep 19, 2026	51-200	176 contacts →
	Partial evidence “EnviroScience is a team of over 150 expert biologists, commercial divers, environmental engineers, and environmental scientists that provides biomonitoring, environmental…” Source: RevenueBase Database · checked Sep 19, 2026
23	Terraphase Engineering INC	Partial evidence	Oakland, CA, United StatesHQ checked Sep 19, 2026	201-500	166 contacts →
	Partial evidence “Terraphase offers cost-effective solutions to complex environmental and engineering challenges.” Source: RevenueBase Database · checked Sep 19, 2026
24	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
25	HRP Associates, INC	Indirect evidence	Farmington, CT, United StatesHQ checked Sep 19, 2026	51-200	155 contacts →
	Indirect evidence “For 40 years, the consulting engineers at HRP have worked together with our clients to assure that they reach their intended business goals and achieve the right solutions to…” 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 compliance 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 compliance firms.
Partial evidence: Its own public description names part of environmental compliance firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name environmental compliance 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 2,372 environmental compliance firms based in the United States

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Environmental compliance firms based in the United States at a glance

As of Sep 19, 2026

47.3%Verified-email coverage

16.2Average contacts per company

1-10Median size (employees)

2.2%Largest-city concentration · Houston

Sep 19, 2026Page data refreshed

Companies by employee count

1-10

1,274

11-50

832

51-200

210

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 2,372 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 compliance 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 compliance 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 compliance 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 compliance 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, 18,230 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 compliance 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 compliance 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 compliance firms are there based in the United States?

RevenueBase identified 2,372 environmental compliance 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?

Montrose Environmental Group, headquartered in Little Rock, tops this list with the largest team on record.

Which city has the most environmental compliance firms?

Houston leads with 52 headquartered companies, followed by Austin (32) and New York (30).

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 18,230 verified decision-maker contacts tracked across these 2,372 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.