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Company lists · Data refreshed September 2026

Top 25 Hydrology consulting firms based in the United States

Compiled by the RevenueBase Data Team Data refreshed Sep 3, 2026 1,205 companies tracked

RevenueBase identified 1,205 hydrology consulting firms headquartered in the United States as of September 2026 and tracks 58,620 professional contacts across them, including 29,687 with verified work emails and 25,186 with mobile numbers. Portland is the largest hub.

This list covers hydrology consulting 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, how directly it supports the match, and when it was last checked. Data refreshed September 3, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase SmartSearch, 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 Match evidence on every row Refreshed Sep 3, 2026 86% judged on-target in blind review
1,205Companies
58,620Contacts tracked
29,687Verified emails
25,186Mobile numbers
Unlock all 1,205 companies Free signup · no credit card · 500 free credits

The 25 largest hydrology consulting firms based in the United States

Ranked by team size
Top 25 of 1,205 hydrology consulting firms based in the United States, ranked by team size, largest first. Data refreshed Sep 3, 2026. Evidence rates how directly each company's own description names hydrology consulting firms: strong (names it), partial (names part of it), indirect (matched on its full profile rather than the summary shown). Click a count to unlock that company's people.
#CompanyHeadquartersEmployeesContacts
1
Tetra TechPartial evidence
Pasadena, CA, United StatesHQ checked Sep 3, 202610001+13,066

“Tetra Tech is the leader in water, environment, and sustainable infrastructure, providing high-end consulting and engineering services for projects worldwide.”

Source: company website · checked Sep 3, 2026
2
Brown And CaldwellIndirect evidence
Walnut Creek, CA, United StatesHQ checked Sep 3, 20261,001-5,0002,455

“Headquartered in Walnut Creek, Calif, Brown and Caldwell is an employee-owned firm with 2,100+ professionals serving clients locally and globally from 52 locations.”

Source: company website · checked Sep 3, 2026
3
Geosyntec ConsultantsPartial evidence
Boca Raton, FL, United StatesHQ checked Sep 3, 20261,001-5,0002,392

“Geosyntec is a consulting and engineering firm that works with private and public sector clients to address new ventures and complex problems involving our environment, natural…”

Source: company website · checked Sep 3, 2026
4
Hazen And SawyerIndirect evidence
New York, NC, United StatesHQ checked Sep 3, 20261,001-5,0002,105

“As Hazen marks 75 years, we celebrate a legacy of absolute commitment to our clients while delivering the best technical work available anywhere.”

Source: company website · checked Sep 3, 2026
5
GEI Consultants, INCIndirect evidence
Woburn, MA, United StatesHQ checked Sep 3, 20261,001-5,0001,577
Source: company website · checked Sep 3, 2026
6
Freese And NicholsPartial evidence
Fort Worth, NC, United StatesHQ checked Sep 3, 20261,001-5,0001,461

“Freese and Nichols is a professional planning, consulting and engineering firm serving clients across the United States.”

Source: company website · checked Sep 3, 2026
7
Apex CompaniesIndirect evidence
Rockville, MD, United StatesHQ checked Sep 3, 20261,001-5,0001,146

“Who is Apex?”

Source: company website · checked Sep 3, 2026
8
VerdantasIndirect evidence
Tampa, OH, United StatesHQ checked Sep 3, 20261,001-5,0001,127

“At Verdantas, we blend engineering and environmental science together with advanced technology and world-renowned labs to create solutions with the big picture in mind.”

Source: company website · checked Sep 3, 2026
9
Barr Engineering COPartial evidence
Minneapolis, United StatesHQ checked Sep 3, 20261,001-5,0001,098

“Barr provides engineering and environmental consulting services to clients across the Midwest, throughout the Americas, and around the world.”

Source: company website · checked Sep 3, 2026
10
ParametrixIndirect evidence
Seattle, CA, United StatesHQ checked Sep 3, 2026501-1,000875

“At Parametrix, we help our clients imagine what's possible.”

Source: company website · checked Sep 3, 2026
11
DUDEKPartial evidence
Encinitas, CA, United StatesHQ checked Sep 3, 2026501-1,000792

“Dudek is an environmental, planning, and engineering consulting firm.”

Source: company website · checked Sep 3, 2026
12
PsomasIndirect evidence
Los Angeles, CA, United StatesHQ checked Sep 3, 2026501-1,000741

“Our award-winning projects are produced through innovation, creativity, and technical expertise.”

Source: company website · checked Sep 3, 2026
13
Environmental Science AssociatesPartial evidence
San Francisco, CA, United StatesHQ checked Sep 3, 2026501-1,000725

“ESA is a 100% employee-owned environmental consulting firm.”

Source: company website · checked Sep 3, 2026
14
Kennedy JenksIndirect evidence
San Francisco, OR, United StatesHQ checked Sep 3, 2026201-500575

“For over 100 years, Kennedy Jenks has provided engineering and scientific solutions for innovative water and environmental projects.”

Source: company website · checked Sep 3, 2026
15
Trihydro CorporationPartial evidence
Laramie, WY, United StatesHQ checked Sep 3, 2026501-1,000571

“Headquartered in Laramie, Wyoming, Trihydro provides environmental consulting, engineering and surveying, air quality and process management, information technology, and water and…”

Source: company website · checked Sep 3, 2026
16
BSC GroupPartial evidence
Boston, MA, United StatesHQ checked Sep 3, 202651-200503

“BSC Group, Inc.(BSC) is a multidisciplinary consulting firm with a staff of more than 200 professionals and offices in Boston, Worcester, Andover, and West Yarmouth, MA, as well…”

Source: company website · checked Sep 3, 2026
17
Rincon ConsultantsPartial evidence
Ventura, CA, United StatesHQ checked Sep 3, 2026501-1,000483

“Rincon Consultants is a multi-disciplinary environmental sciences, planning, and engineering consulting firm that provides quality professional services to government and industry.”

Source: company website · checked Sep 3, 2026
18
Anchor QEAPartial evidence
Seattle, MD, United StatesHQ checked Sep 3, 2026501-1,000478

“Headquartered in Seattle, Washington, Anchor QEA is a nationally recognized environmental science and engineering consulting firm specializing in aquatic, shoreline, and water…”

Source: company website · checked Sep 3, 2026
19
Ae2s Advanced Engineering And Environmental Services, LLCPartial evidence
Grand Forks, ND, United StatesHQ checked Sep 3, 2026201-500335

“AE2S is a specialized civil/environmental consulting engineering firm that provides professional services and our unique brand of extreme client service to clients in the upper…”

Source: company website · checked Sep 3, 2026
20
CME AssociatesIndirect evidence
Parlin, NJ, United StatesHQ checked Sep 3, 2026201-500333

“CME Associates, with eight (8) office locations throughout New Jersey, provides a complete range of Environmental, Geotechnical, Engineering, Surveying and Planning services.”

Source: company website · checked Sep 3, 2026
21
LSAPartial evidence
Irvine, CA, United StatesHQ checked Sep 3, 2026201-500331

“LSA is a diversified environmental, transportation, and community planning firm that evolved from a small consulting firm.”

Source: company website · checked Sep 3, 2026
22
Ardaman & AssociatesIndirect evidence
Orlando, FL, United StatesHQ checked Sep 3, 2026201-500308

“Ardaman & Associates, Inc.”

Source: company website · checked Sep 3, 2026
23
West YostPartial evidence
Davis, OR, United StatesHQ checked Sep 3, 2026201-500279

“West Yost is a water-focused consulting engineering firm ranked by Fortune Magazine as one of the “Best Small and Medium Workplaces in Consulting and Professional Services” 2023 -…”

Source: company website · checked Sep 3, 2026
24
Wetland Studies And Solutions, Inc. Wssi , A Davey Tree CompanyPartial evidence
Gainesville, VA, United StatesHQ checked Sep 3, 2026201-500267

“For more than 30 years, WSSI has been the trusted partner in environmental, regulatory, cultural resources, and water resources engineering consulting.”

Source: company website · checked Sep 3, 2026
25
Christopher B. Burke Engineering, LTDIndirect evidence
Rosemont, IL, United StatesHQ checked Sep 3, 2026201-500259

“Christopher B.”

Source: company website · checked Sep 3, 2026

Showing 25 of 1,205 hydrology consulting firms based in the United States

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Hydrology consulting firms based in the United States at a glance

As of Sep 3, 2026
1-10Median size (employees)
PortlandLargest hub · 23 HQs
25,186Contacts with mobile numbers
Sep 3, 2026Data refreshed

Companies by employee count

1-10
665
11-50
376
51-200
110
201-500
25
501-1,000
9
1,001-5,000
12
10001+
2

Verified emails by last verification

0–30
0
31–60
2,576
61–90
17,068
90–180
9,854
180+
189

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 hydrology consulting firms, so some rows will be adjacent to the category rather than pure plays. The description and evidence 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 SmartSearch, 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 “hydrology consulting firms”. Matching reads each company's description, not its industry code or its name.
What we exclude
Companies whose own description does not clearly place them among hydrology consulting 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 an evidence 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, 29,687 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 3, 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.

Frequently asked

How many hydrology consulting firms are there based in the United States?

RevenueBase identified 1,205 hydrology consulting 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?

Tetra Tech, headquartered in Pasadena, tops this list with the largest team on record.

Which city has the most hydrology consulting firms?

Portland leads with 23 headquartered companies, followed by Houston (20) and San Diego (14).

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 29,687 verified decision-maker contacts tracked across these 1,205 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 3, 2026.

Ready to reach these companies? Verified emails and direct dials for all 1,205 hydrology consulting firms based in the United States. Start with a free account, no credit card.

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Related lists

Browse: Companies home · All United States lists · All Hydrology consulting firms lists · New lists

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 SmartSearch, 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.

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