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The latest NJBIZ Leads & Data research compilation ranks the state’s top environmental firms based on the number of New Jersey employees. 

Colliers Engineering & Design held the No. 1 position. Founded in 1984 and based in Holmdel, the firm reported environmental billings of $13 million in 2025 and employs 637 people in New Jersey. Kevin Haney leads the firm. 

Based in Piscataway, AECOM ranks second on the list. With a team of 590 New Jersey employees, the firm reported billings of $34.7 million last year. 

At No. 3, Langan Engineering and Environmental Services, founded in 1970 and based in Parsippany, reported billings of $190.4 million under David Gockel, with 550 employees in the state. 

Mott MacDonald, in fourth place, traces its founding to 1866. The Iselin-based firm reported billings of $190.8 million in 2025 and employs 346 people in New Jersey. 

South Hackensack-based Boswell, founded in 1924, rounds out the top five. The company has 275 employees in state and reported billings of $6.86 million last year. 

Provident Bank is the Premium Publication Sponsor of NJBIZ’s 2026 Book of Lists.

Go to the NJBIZ Leads & Data Center to download the complete Environmental Firms list or any other NJBIZ list. Subscribe to NJBIZ’s Leads & Data to gain year-round access to the data from NJBIZ lists. 

Claude.ai assisted with the creation of this article based on NJBIZ data.