Company lists · Data refreshed September 2026

Top 25 Environmental law firms based in Washington, United States

Name: Environmental law firms based in Washington, United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 12, 2026 127 companies tracked

RevenueBase identified 127 environmental law firms headquartered in Washington, United States as of September 2026 and tracks 9,111 professional contacts across them, including 5,870 with verified work emails and 4,739 with mobile numbers. Washington is the largest hub.

This list covers environmental law firms headquartered in Washington, 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 12, 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 12, 2026 86% judged on-target in blind review

127Companies

9,111Contacts tracked

5,870Verified emails

4,739Mobile numbers

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The 25 largest environmental law firms based in Washington, United States

Ranked by team size

Top 25 of 127 environmental law firms based in Washington, United States, ranked by team size, largest first. Data refreshed Sep 12, 2026. RevenueBase Smart Search rates how each company's information relates to environmental law 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	Arnold & Porter	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1,001-5,000	2,333 contacts →
	Indirect evidence “Arnold & Porter combines sophisticated regulatory, litigation, and transactional capabilities to resolve clients’ most complex issues.” Source: RevenueBase Database · checked Sep 12, 2026
2	Venable LLP	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1,001-5,000	1,790 contacts →
	Partial evidence “Committed to Your Success – As a law firm of more than 900 professionals, Venable delivers legal services globally in every area of regulatory compliance, government affairs…” Source: RevenueBase Database · checked Sep 12, 2026
3	Crowell & Moring	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1,001-5,000	1,602 contacts →
	Partial evidence “Crowell & Moring is an international law firm with operations in the United States, Europe, MENA, and Asia.” Source: RevenueBase Database · checked Sep 12, 2026
4	Wiley Rein LLP	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	501-1,000	576 contacts →
	Indirect evidence “Founded in 1983, Wiley is a dominant presence in the nation’s capital.” Source: RevenueBase Database · checked Sep 12, 2026
5	Beveridge & Diamond PC	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	201-500	328 contacts →
	Indirect evidence “Beveridge & Diamond’s 170+ lawyers in 7 U.S.” Source: RevenueBase Database · checked Sep 12, 2026
6	Dickstein Shapiro LLP	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	501-1,000	292 contacts →
	Indirect evidence “Dickstein Shapiro LLP, Market Leading Specialty Firm (SM), is internationally recognized for its work with clients, from start-ups to Fortune 500 corporations.” Source: RevenueBase Database · checked Sep 12, 2026
7	Hausfeld	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	201-500	267 contacts →
	Indirect evidence “Hausfeld successfully resolves disputes for its clients, driven by its bold approach and pioneering experience.” Source: RevenueBase Database · checked Sep 12, 2026
8	Keller And Heckman LLP	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	51-200	230 contacts →
	Partial evidence “Keller and Heckman, founded in 1962, has a broad practice in the areas of regulatory law, public policy, and litigation, serving both domestic and international clients.” Source: RevenueBase Database · checked Sep 12, 2026
9	VAN Ness Feldman LLP	Strong evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	51-200	174 contacts →
	Strong evidence “Van Ness Feldman is a nationally recognized mid-sized law firm specializing in the areas of energy, environment, and natural resources law and policy, with offices in Washington…” Source: RevenueBase Database · checked Sep 12, 2026
10	Hollingsworth LLP	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	51-200	112 contacts →
	Indirect evidence “Hollingsworth LLP is among the nation’s leading litigation firms.” Source: RevenueBase Database · checked Sep 12, 2026
11	Holtzman Vogel	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	51-200	80 contacts →
	Indirect evidence “HOLTZMAN VOGEL PROTECTS THE HIGHEST PROFILE VOICES IN BUSINESS, POLITICS AND ADVOCACY For 25 years, Holtzman Vogel has represented Fortune 500 companies, non-profits, high net…” Source: RevenueBase Database · checked Sep 12, 2026
12	Center For International Environmental LAW Ciel	Strong evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	51-200	74 contacts →
	Strong evidence “The Center for International Environmental Law (CIEL) uses the power of the law to protect the environment, promote human health, and ensure a just and sustainable society.” Source: RevenueBase Database · checked Sep 12, 2026
13	Reno & Cavanaugh, Pllc	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	51-200	73 contacts →
	Partial evidence “Since 1977, Reno & Cavanaugh has been a national law firm dedicated to strengthening communities through strategic use of public and private resources.” Source: RevenueBase Database · checked Sep 12, 2026
14	DOW Lohnes	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	201-500	73 contacts →
	Indirect evidence “On January 1, 2014, Dow Lohnes merged with Cooley LLP.” Source: RevenueBase Database · checked Sep 12, 2026
15	Peer Consultants, P.C	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	51-200	71 contacts →
	Indirect evidence “In 1978, PEER was established under Dr.” Source: RevenueBase Database · checked Sep 12, 2026
16	HWG LLP	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	51-200	70 contacts →
	Partial evidence “HWG LLP is a boutique law firm designed to offer clients access to top tier legal talent without unnecessary overhead.” Source: RevenueBase Database · checked Sep 12, 2026
17	Conn Maciel Carey LLP	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	46 contacts →
	Partial evidence “Conn Maciel Carey LLP is a boutique law firm focused on Labor & Employment, Workplace Safety - OSHA/MSHA, and Litigation.” Source: RevenueBase Database · checked Sep 12, 2026
18	John & Hengerer LLP	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	n/a	46 contacts →
	Indirect evidence “John & Hengerer LLP represents and advises energy companies, inlcuding natural gas producers, importers, processors, and marketers; gas and liquids pipeline operators; gas storage…” Source: RevenueBase Database · checked Sep 12, 2026
19	Bergeson & Campbell, P.C	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	40 contacts →
	Indirect evidence Source: RevenueBase Database · checked Sep 12, 2026
20	Tiber Hudson LLC	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	36 contacts →
	Partial evidence “Tiber Hudson LLC is a boutique law firm focused in providing legal services including complex commercial litigation, complex commercial transactions, corporate structure and…” Source: RevenueBase Database · checked Sep 12, 2026
21	Spiegel & Mcdiarmid LLP	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	29 contacts →
	Indirect evidence “Spiegel & McDiarmid LLP was formed to represent the public side of our nation’s critical infrastructure industries, including energy, telecommunications and transportation.” Source: RevenueBase Database · checked Sep 12, 2026
22	Duncan, Weinberg, Genzer & Pembroke, P.C. Dwgp	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	28 contacts →
	Indirect evidence “Since its founding in 1971, DWG & P, has provided a broad range of counseling, regulatory, litigation and legislative services to clients in every region of the country.” Source: RevenueBase Database · checked Sep 12, 2026
23	Cuneo, Gilbert & Laduca, LLP	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	26 contacts →
	Indirect evidence “We practice advocacy-and only advocacy.” Source: RevenueBase Database · checked Sep 12, 2026
24	Trister, Ross, Schadler & Gold, Pllc	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	26 contacts →
	Indirect evidence “Trister, Ross, Schadler & Gold, PLLC combines personalized client service with decades of broad experience and specialized legal expertise.” Source: RevenueBase Database · checked Sep 12, 2026
25	GKG Law, P.C	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	26 contacts →
	Partial evidence “Beginning in 1955, GKG Law remains dedicated to crafting the best approach to meet our clients’ needs.” Source: RevenueBase Database · checked Sep 12, 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 law 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 law firms.
Partial evidence: Its own public description names part of environmental law firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name environmental law 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 127 environmental law firms based in Washington, United States

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Environmental law firms based in Washington, United States at a glance

As of Sep 12, 2026

64.4%Verified-email coverage

52.0%Mobile-number coverage

71.7Average contacts per company

1-10Median size (employees)

104.7%Largest-city concentration · Washington

Sep 12, 2026Page data refreshed

Companies by employee count

1-10

11-50

51-200

201-500

501-1,000

1,001-5,000

Freshness & accuracy

How recently the business emails were verified and the company information checked

Email last verified

Median 14.0d

4,9290–30

90031–60

2361–90

190–180

17180+

Company record updated

Median 63.0d

00–30

4,47831–60

3,60861–90

69190–180

334180+

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 law 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 Washington, United States whose own description of what they do matches “environmental law 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 law 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 law firms, and records with no verified work email. Companies headquartered outside Washington 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, 5,870 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 12, 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 law firms by metro in the United States

Environmental law firms in Washington133
Environmental law firms in New York127
Environmental law firms in Houston112
Environmental law firms in Chicago77
Environmental law firms in Los Angeles71
Environmental law firms in Austin62
Environmental law firms in San Francisco58
Environmental law firms in Dallas58

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 law 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 law firms are there based in Washington, United States?

RevenueBase identified 127 environmental law firms headquartered in Washington, 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?

Arnold & Porter, headquartered in Washington, tops this list with the largest team on record.

Which city has the most environmental law firms?

Washington leads with 133 headquartered companies, followed by New York (127) and Houston (112).

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 5,870 verified decision-maker contacts tracked across these 127 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 12, 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.