Company lists · Data refreshed September 2026

Top 25 Environmental consultancy firms based in Washington, United States

Name: Environmental consultancy 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 59 companies tracked

RevenueBase identified 59 environmental consultancy firms headquartered in Washington, United States as of September 2026 and tracks 551 professional contacts across them, including 192 with verified work emails and 198 with mobile numbers. Houston is the largest hub.

This list covers environmental consultancy 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

59Companies

551Contacts tracked

192Verified emails

198Mobile numbers

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

Ranked by team size

Top 25 of 59 environmental consultancy 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 consultancy 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	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
2	Baumann Consulting	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	51-200	63 contacts →
	Indirect evidence “Baumann Consulting is driven to deliver solutions for a carbon-neutral real estate industry.” Source: RevenueBase Database · checked Sep 12, 2026
3	Northbridge	Partial evidence	Washington, United StatesHQ checked Sep 12, 2026	11-50	24 contacts →
	Partial evidence “At Northbridge, we provide our clients with the tools and expertise to help solve complex financial, policy, and environmental challenges.” Source: RevenueBase Database · checked Sep 12, 2026
4	The Clark Group LLC	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	19 contacts →
	Partial evidence “The Clark Group is an environmental policy consulting firm that provides a broad range of services to government, private and nonprofit clients.” Source: RevenueBase Database · checked Sep 12, 2026
5	E&w LAW	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	18 contacts →
	Partial evidence “At Earth & Water, we are more than lawyers – we’re strategic advisors with unique experience who advance our clients’ interests across a broad range of environmental and business…” Source: RevenueBase Database · checked Sep 12, 2026
6	Numark Associates, INC	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	15 contacts →
	Indirect evidence Source: RevenueBase Database · checked Sep 12, 2026
7	Co2efficient	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	14 contacts →
	Indirect evidence “CO2EFFICIENT LLC (COEFFICIENT) was founded in 2017 as a mission-focused Washington, D.C.” Source: RevenueBase Database · checked Sep 12, 2026
8	Blackwoods Group	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	14 contacts →
	Indirect evidence “Blackwoods Group is an agriculture and natural resource consulting firm that provides a variety of services ranging from government relations to development and implementation of…” Source: RevenueBase Database · checked Sep 12, 2026
9	Sustainable Strategies DC	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	11 contacts →
	Indirect evidence “Sustainable Strategies DC is a government affairs and strategic consulting firm based in Washington, DC, that helps clients secure resources for community revitalization and tools…” Source: RevenueBase Database · checked Sep 12, 2026
10	TSG Consulting	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	51-200	11 contacts →
	Indirect evidence “For over 30 years, TSG has provided companies around the world with regulatory guidance and scientific expertise.” Source: RevenueBase Database · checked Sep 12, 2026
11	TWW	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	10 contacts →
	Indirect evidence “The Wright Way Enterprises (TWW) is certified as an SBA 8(a) and HUBZone small business and DC Certified Business Enterprise (CBE), stewarding organizations in addressing the…” Source: RevenueBase Database · checked Sep 12, 2026
12	Green Strategies, INC	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	8 contacts →
	Indirect evidence “Green Strategies Inc.” Source: RevenueBase Database · checked Sep 12, 2026
13	The Climate Board	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	7 contacts →
	Indirect evidence “The Climate Board builds AI-enhanced data products for corporate climate teams, closing the gap between infrequent assessments and real-time risk.” Source: RevenueBase Database · checked Sep 12, 2026
14	Green Capitol	Partial evidence	Washington, United StatesHQ checked Sep 12, 2026	1-10	7 contacts →
	Partial evidence “Green Capitol LLC works on sustainable development policy at the state, federal and international levels, serving clients on agriculture, energy and environment concerns via…” Source: RevenueBase Database · checked Sep 12, 2026
15	Energy Shrink, LLC	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	6 contacts →
	Partial evidence “Energy Shrink is an environmental consulting practice specialized in sustainability and energy efficiency in buildings, that is, high-performance or green buildings.” Source: RevenueBase Database · checked Sep 12, 2026
16	Deborah Brosnan & Associates	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	4 contacts →
	Indirect evidence “Leading and innovative company that finding solutions, bridging gaps and driving positive action for clients and the planet.” Source: RevenueBase Database · checked Sep 12, 2026
17	Sustainability Frameworks	Partial evidence	Washington, United StatesHQ checked Sep 12, 2026	1-10	4 contacts →
	Partial evidence “Sustainability Frameworks helps its public and private sector clients develop strategies to manage their environmental and social risks and opportunities, optimize their…” Source: RevenueBase Database · checked Sep 12, 2026
18	JG Global Advisory, LLC	Strong evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	4 contacts →
	Strong evidence “JG Global Advisory, LLC is a minority, woman-owned small business (WOSB) consultancy providing advisory services and integrated solutions for environmental and international…” Source: RevenueBase Database · checked Sep 12, 2026
19	Warwick Group Consultants, LLC	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	3 contacts →
	Partial evidence “Warwick Group Consultants is the Nation's premier consulting firm for local governments with coastal projects involving beach nourishment, dredging, aquatic ecosystem restoration…” Source: RevenueBase Database · checked Sep 12, 2026
20	Greening Urban LLC	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	3 contacts →
	Indirect evidence “Greening Urban is a civil engineering firm with built projects in Washington, D.C; Maryland; and Virginia.” Source: RevenueBase Database · checked Sep 12, 2026
21	Pagitsas Advisors	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	3 contacts →
	Indirect evidence “Pagitsas Advisors is a professional services firm specializing in the commercialization of sustainability.” Source: RevenueBase Database · checked Sep 12, 2026
22	Ardeidae Group	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	2 contacts →
	Indirect evidence “Strategic advisory services for the triple bottom line.” Source: RevenueBase Database · checked Sep 12, 2026
23	Watershed Results LLC	Partial evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	2 contacts →
	Partial evidence “Greg Schildwachter is a professional conservationist serving businesses and mission-organizations with his credentials in wildlife science and skill as a lobbyist and consultant.” Source: RevenueBase Database · checked Sep 12, 2026
24	Adloris, LTD	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	11-50	1 contacts →
	Indirect evidence “Adloris, ltd has provided data-driven and sustainability-oriented advice to our clients for over 15 years.” Source: RevenueBase Database · checked Sep 12, 2026
25	Akhandataa Solutions For Impact	Indirect evidence	Washington, DC, United StatesHQ checked Sep 12, 2026	1-10	1 contacts →
	Indirect evidence “AKHANDATAA is in the business of creating, evaluating, and fostering SOLUTIONS FOR IMPACT with INTEGRITY.” 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 consultancy 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 consultancy firms.
Partial evidence: Its own public description names part of environmental consultancy firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name environmental consultancy 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 59 environmental consultancy firms based in Washington, United States

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

As of Sep 12, 2026

34.8%Verified-email coverage

35.9%Mobile-number coverage

9.3Average contacts per company

1-10Median size (employees)

167.8%Largest-city concentration · Houston

Sep 12, 2026Page data refreshed

Companies by employee count

1-10

11-50

51-200

Freshness & accuracy

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

Email last verified

Median 14.0d

1650–30

2731–60

061–90

090–180

0180+

Company record updated

Median 61.0d

00–30

26831–60

21261–90

4990–180

22180+

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 consultancy 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 consultancy 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 consultancy 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 consultancy 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, 192 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 consultancy firms by metro in the United States

Environmental consultancy firms in Houston99
Environmental consultancy firms in New York77
Environmental consultancy firms in Seattle54
Environmental consultancy firms in Washington53
Environmental consultancy firms in Denver51
Environmental consultancy firms in Chicago51
Environmental consultancy firms in Portland46

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

RevenueBase identified 59 environmental consultancy 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?

Peer Consultants, P.C, headquartered in Washington, tops this list with the largest team on record.

Which city has the most environmental consultancy firms?

Houston leads with 99 headquartered companies, followed by New York (77) and Seattle (54).

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 192 verified decision-maker contacts tracked across these 59 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.