Company lists · Data refreshed September 2026

Top 25 Hydrogeology consulting services based in the United States

Name: Hydrogeology consulting services based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 21, 2026 1,530 companies tracked

RevenueBase identified 1,530 hydrogeology consulting services headquartered in the United States as of September 2026 and tracks 56,546 professional contacts across them, including 26,616 with verified work emails. Houston is the largest hub.

This list covers hydrogeology consulting services 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 21, 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 21, 2026 86% judged on-target in blind review

1,530Companies

56,546Contacts tracked

26,616Verified emails

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The 25 largest hydrogeology consulting services based in the United States

Ranked by team size

Top 25 of 1,530 hydrogeology consulting services based in the United States, ranked by team size, largest first. Data refreshed Sep 21, 2026. RevenueBase Smart Search rates how each company's information relates to hydrogeology consulting services: 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	Tetra Tech	Indirect evidence	Pasadena, CA, United StatesHQ checked Sep 21, 2026	10001+	12,999 contacts →
	Indirect evidence “Tetra Tech is the leader in water, environment and sustainable infrastructure, providing high-end technical and engineering services for projects worldwide.” Source: RevenueBase Database · checked Sep 21, 2026
2	Terracon	Partial evidence	Olathe, KS, United StatesHQ checked Sep 21, 2026	5,001-10,000	6,113 contacts →
	Partial evidence “Terracon is a 100 percent employee-owned consulting engineering firm providing quality services to clients.” Source: RevenueBase Database · checked Sep 21, 2026
3	ECS Group Of Companies	Partial evidence	Chantilly, VA, United StatesHQ checked Sep 21, 2026	1,001-5,000	2,210 contacts →
	Partial evidence “ECS Group of Companies is a Chantilly, VA-based consulting engineering firm.” Source: RevenueBase Database · checked Sep 21, 2026
4	Hazen And Sawyer	Indirect evidence	New York, NY, United StatesHQ checked Sep 21, 2026	1,001-5,000	2,100 contacts →
	Indirect evidence “As Hazen marks 75 years, we celebrate a legacy of absolute commitment to our clients while delivering the best technical work available anywhere.” Source: RevenueBase Database · checked Sep 21, 2026
5	Knight Piesold	Partial evidence	Denver, CO, United StatesHQ checked Sep 21, 2026	1,001-5,000	1,231 contacts →
	Partial evidence “Knight Piésold is an employee-owned, global consulting firm providing specialist services to the mining, power, water resources, and infrastructure industries.” Source: RevenueBase Database · checked Sep 21, 2026
6	GZA Geoenvironmental, INC	Indirect evidence	Norwood, MA, United StatesHQ checked Sep 21, 2026	501-1,000	880 contacts →
	Indirect evidence “Founded in 1964 as a soils and foundations specialty consultant, GZA GeoEnvironmental, Inc.(GZA) has grown into a full-service company providing its clients with highly…” Source: RevenueBase Database · checked Sep 21, 2026
7	Raba Kistner, INC	Indirect evidence	San Antonio, TX, United StatesHQ checked Sep 21, 2026	501-1,000	582 contacts →
	Indirect evidence “Founded in 1968, Raba Kistner Inc.” Source: RevenueBase Database · checked Sep 21, 2026
8	Trihydro Corporation	Partial evidence	Laramie, WY, United StatesHQ checked Sep 21, 2026	501-1,000	577 contacts →
	Partial evidence “Headquartered in Laramie, Wyoming, Trihydro provides environmental consulting, engineering and surveying, air quality and process management, information technology, and water and…” Source: RevenueBase Database · checked Sep 21, 2026
9	Nova Engineering And Environmental, LLC	Partial evidence	Kennesaw, GA, United StatesHQ checked Sep 21, 2026	501-1,000	518 contacts →
	Partial evidence “Established in 1996, NOVA was originally founded to provide Environmental Consulting, Geotechnical Engineering, and Construction Materials Testing and Inspection services to the…” Source: RevenueBase Database · checked Sep 21, 2026
10	Anchor QEA	Partial evidence	Seattle, WA, United StatesHQ checked Sep 21, 2026	501-1,000	479 contacts →
	Partial evidence “Headquartered in Seattle, Washington, Anchor QEA is a nationally recognized environmental science and engineering consulting firm specializing in aquatic, shoreline, and water…” Source: RevenueBase Database · checked Sep 21, 2026
11	Rincon Consultants	Partial evidence	Ventura, CA, United StatesHQ checked Sep 21, 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 21, 2026
12	Ninyo & Moore, A Socotec Company	Indirect evidence	San Diego, CA, United StatesHQ checked Sep 21, 2026	501-1,000	449 contacts →
	Indirect evidence “Ninyo & Moore was acquired by SOCOTEC US.” Source: RevenueBase Database · checked Sep 21, 2026
13	Ae2s Advanced Engineering And Environmental Services, LLC	Partial evidence	Grand Forks, ND, United StatesHQ checked Sep 21, 2026	201-500	339 contacts →
	Partial evidence “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: RevenueBase Database · checked Sep 21, 2026
14	CME Associates	Indirect evidence	Parlin, NJ, United StatesHQ checked Sep 21, 2026	201-500	336 contacts →
	Indirect evidence “CME Associates, with eight (8) office locations throughout New Jersey, provides a complete range of Environmental, Geotechnical, Engineering, Surveying and Planning services.” Source: RevenueBase Database · checked Sep 21, 2026
15	Tata & Howard, INC	Partial evidence	Marlborough, MA, United StatesHQ checked Sep 21, 2026	51-200	315 contacts →
	Partial evidence “Tata & Howard is a 100% employee owned, award-winning, specialized consulting engineering firm dedicated to providing superior client service coupled with delivering…” Source: RevenueBase Database · checked Sep 21, 2026
16	Froehling & Robertson, INC	Indirect evidence	Richmond, VA, United StatesHQ checked Sep 21, 2026	201-500	312 contacts →
	Indirect evidence “Established in 1881, Froehling & Robertson, Inc.” Source: RevenueBase Database · checked Sep 21, 2026
17	Ardaman & Associates	Indirect evidence	Orlando, FL, United StatesHQ checked Sep 21, 2026	201-500	311 contacts →
	Indirect evidence “Ardaman & Associates, Inc.” Source: RevenueBase Database · checked Sep 21, 2026
18	Hillis-Carnes Engineering Associates, INC	Partial evidence	Annapolis Junction, MD, United StatesHQ checked Sep 21, 2026	201-500	299 contacts →
	Partial evidence “Hillis-Carnes Engineering Associates, Inc.(HCEA) is a Mid-Atlantic based, multi-disciplined consulting engineering firm.” Source: RevenueBase Database · checked Sep 21, 2026
19	ENGEO	Indirect evidence	San Ramon, CA, United StatesHQ checked Sep 21, 2026	201-500	282 contacts →
	Indirect evidence “ENGEO Incorporated is an award-winning, employee-owned comprehensive provider of more than 400 geotechnical and civil engineers, geologists, GIS experts, environmental scientists…” Source: RevenueBase Database · checked Sep 21, 2026
20	West Yost	Partial evidence	Davis, CA, United StatesHQ checked Sep 21, 2026	201-500	279 contacts →
	Partial evidence “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: RevenueBase Database · checked Sep 21, 2026
21	Wetland Studies And Solutions, Inc. Wssi , A Davey Tree Company	Partial evidence	Gainesville, VA, United StatesHQ checked Sep 21, 2026	201-500	268 contacts →
	Partial evidence “For more than 30 years, WSSI has been the trusted partner in environmental, regulatory, cultural resources, and water resources engineering consulting.” Source: RevenueBase Database · checked Sep 21, 2026
22	Intera Incorporated	Partial evidence	Austin, TX, United StatesHQ checked Sep 21, 2026	201-500	259 contacts →
	Partial evidence “Established in 1974, INTERA is a geosciences and engineering consulting firm focused on providing water resources and supply, environmental, mining, radioactive waste isolation…” Source: RevenueBase Database · checked Sep 21, 2026
23	Geotek	Partial evidence	Las Vegas, NV, United StatesHQ checked Sep 21, 2026	201-500	215 contacts →
	Partial evidence “Incorporated in 1997, GeoTek is a full service consulting engineering firm specializing in geotechnical engineering, construction materials testing, special inspection, and…” Source: RevenueBase Database · checked Sep 21, 2026
24	BSK Associates	Indirect evidence	Fresno, CA, United StatesHQ checked Sep 21, 2026	201-500	201 contacts →
	Indirect evidence “Employee-Owned.” Source: RevenueBase Database · checked Sep 21, 2026
25	Geocon	Partial evidence	San Diego, CA, United StatesHQ checked Sep 21, 2026	201-500	197 contacts →
	Partial evidence “Geocon is a California corporation established in 1971 as a professional engineering consulting firm providing comprehensive geotechnical engineering, geotechnical…” Source: RevenueBase Database · checked Sep 21, 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: hydrogeology consulting services. 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 hydrogeology consulting services.
Partial evidence: Its own public description names part of hydrogeology consulting services, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name hydrogeology consulting services. 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 1,530 hydrogeology consulting services based in the United States

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Hydrogeology consulting services based in the United States at a glance

As of Sep 21, 2026

47.1%Verified-email coverage

37.0Average contacts per company

1-10Median size (employees)

3.3%Largest-city concentration · Houston

Sep 21, 2026Page data refreshed

Companies by employee count

1-10

776

11-50

528

51-200

171

201-500

501-1,000

1,001-5,000

5,001-10,000

10001+

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 1,530 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 hydrogeology consulting services, 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 “hydrogeology consulting services”. 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 hydrogeology consulting services), 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 hydrogeology consulting services, 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, 26,616 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 21, 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.

Hydrogeology consulting services by metro

Hydrogeology consulting services in Houston50
Hydrogeology consulting services in Denver28

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 hydrogeology consulting services, 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 hydrogeology consulting services are there based in the United States?

RevenueBase identified 1,530 hydrogeology consulting services 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 hydrogeology consulting services?

Houston leads with 50 headquartered companies, followed by Denver (28) and Irvine (15).

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 26,616 verified decision-maker contacts tracked across these 1,530 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 21, 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.