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Company lists · Data verified August 2026

Top 25 Environmental consultancy firms based in the United States

Compiled by the RevenueBase Data Team Verified Aug 28, 2026 4,594 companies tracked

There are 4,594 environmental consultancy firms headquartered in the United States (RevenueBase, August 2026). RevenueBase tracks 157,371 professional contacts across them, including 72,356 with verified work emails and 66,482 with mobile numbers. Houston is the largest hub.

This list covers environmental consultancy 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. Data current as of August 28, 2026.

4,594Companies
157,371Contacts tracked
72,356Verified emails
66,482Mobile numbers
Unlock all 4,594 companies Free account · no credit card · 2 minutes

The 25 largest environmental consultancy firms based in the United States

Ranked by team size
Top 25 of 4,594 environmental consultancy firms based in the United States, ranked by team size, largest first. Data verified Aug 28, 2026. Click a count to unlock that company's people.
#CompanyHQEmployeesContactsVerified emails
1TerraconTustin, CA5,001-10,0006,0243,163
2GolderHouston, TX5,001-10,0003,1831,044
3APTIMWichita, KS1,001-5,0002,6441,098
4Brown And CaldwellWalnut Creek, CA1,001-5,0002,4551
5Geosyntec ConsultantsBoca Raton, FL1,001-5,0002,3921,594
6ECS Group Of CompaniesFredericksburg, VA1,001-5,0002,2011,061
7Civil & Environmental Consultants, INCMartinsburg, WV1,001-5,0002,152945
8Langan Engineering & Environmental ServicesEl Segundo, CA1,001-5,0002,1361,662
9RicardoCalifornia, MD1,001-5,0002,111955
10Hazen And SawyerRaleigh, NC1,001-5,0002,1051,457
11Swca Environmental ConsultantsPhoenix, AZ1,001-5,0001,6181,159
12GEI Consultants, INCWoburn, MA1,001-5,0001,5771,237
13UESHouston, TX1,001-5,0001,571879
14Montrose Environmental GroupLittle Rock, AR1,001-5,0001,516846
15Partner Engineering & Science, INCPasadena, CA1,001-5,0001,348984
16SCS EngineersLong Beach, CA1,001-5,0001,191675
17Apex CompaniesRockville, MD1,001-5,0001,146591
18Bge, INCVero Beach, FL1,001-5,0001,129682
19VerdantasToledo, OH1,001-5,0001,127795
20Barr Engineering COWashington1,001-5,0001,098828
21Braun Intertec CorporationAmarillo, TX1,001-5,0001,054691
22CardnoLone Tree, CO1,001-5,000991242
23Trinity ConsultantsDallas, TX1,001-5,000949615
24Alliance Technical GroupPittsburgh, PA1,001-5,000946549
25ParametrixBerkeley, CA501-1,000875678

Showing 25 of 4,594 environmental consultancy firms based in the United States

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Environmental consultancy firms based in the United States at a glance

As of Aug 28, 2026
1-10Median size (employees)
HoustonLargest hub · 99 HQs
66,482Contacts with mobile numbers
0Emails re-verified in last 30 days

Companies by employee count

1-10
2,578
11-50
1,443
51-200
401
201-500
81
501-1,000
31
1,001-5,000
37
5,001-10,000
6

Environmental consultancy firms by metro

MetroCompanies
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

How this list was built

Source
The RevenueBase company graph: 21.3 million companies and 398.9 million professional contacts resolved from primary sources.
Inclusion
Companies whose own business descriptions match “environmental consultancy firms”, with match quality audited by blind human judging, and headquartered in the United States.
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
Contact records re-verify on a rolling cadence; 0 contacts on this list were re-verified in the last 30 days.
Refresh
Lists are refreshed periodically as the underlying company graph is re-verified. Last verified Aug 28, 2026.

Frequently asked

How many environmental consultancy firms are there based in the United States?

There are 4,594 environmental consultancy firms headquartered in the United States as of August 2026 (RevenueBase).

What is the largest company on this list?

Terracon, headquartered in Tustin, 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 72,356 verified decision-maker contacts tracked across these 4,594 companies.

How current is this list?

The list is refreshed periodically as the underlying company graph is re-verified. It was last verified on August 28, 2026.

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Related lists

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About this data

RevenueBase is a B2B contact data platform. Its company graph covers 21.3 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, the same data that powers RevenueBase's B2B data products and the free research portal.

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