Major commercial and residential projects associated with OCVibe, Rancho Mission Viejo, UCI, John Wayne Airport and Irvine Company kept 21 of the county’s largest engineering firms busy in 2025, though local billings still dropped 3% year-over-year to $1.3 billion.
Bill Parente, general manager of Southern California operations at No. 1-ranked Fluor Corp., said that headwinds and uncertainties about “disrupted supply chains, constrained access to critical materials and fluctuating commodity prices” are dictating company priorities.
“Geopolitical volatility has become one of the defining forces shaping how our clients plan, invest and operate in 2026,” Parente told the Business Journal.
One of its ongoing projects, the LAX Automated People Mover, now dubbed SkyLink, started construction in 2019.
Despite the overall downturn in billings, more than half of the local offices did report growth.
Salas O’Brien reported the largest increase of 49% to $35.4 million in 2025 billings. The Irvine-based firm jumped in rankings on this year’s list, from No. 15 to 11.
Chairman and Chief Executive Darin Anderson said his firm has been focused on industries with high growth and sustained demand, listing healthcare, higher education, defense and federal government, life sciences, entertainment, aviation, advanced manufacturing and data centers as examples.
“Many of these same sectors are among the fastest growing in Orange County and the broader region, which positions us well to grow alongside the local economy,” Anderson told the Business Journal.
He added that the region’s economy is also a growth factor, citing that “steady demand” stems from clients looking to do business in OC.
Companywide billings from the 21 engineering companies inched up 1% to $60.4 billion, according to Business Journal research.
As of June, the firms reported 982 licensed engineers, a 5.6% increase from a year ago. The total headcount was 3,631 employees in Orange County, up 5.5% from last year.
Aecom, Verdantas Fall in OC Billings
Anderson said doors continue to open for Salas O’Brien in Orange County because “our clients want a firm capable of both large-scale technical work and trusted community relationships that span decades.”
Companywide, Salas O’Brien grew 7.1% to $894 million.
The CEO added the firm has “more technical depth, more specialized expertise, and more capacity to take on the complex projects this region needs.”
The Santa Ana office of Psomas reported billings of $48.4 million for last year, up 27% from the year before and driving the Los Angeles-based firm’s companywide growth of 5.5% to $204 million.
Las Vegas-based Wright Engineers, which has an office in Irvine, rose 38% to $5.8 million in local billings, ranking No. 21.
Four firms reported decreases in 2025 billings, including No. 2 Aecom Technical Services, which generated billings of $131.5 million, down 38%; and No. 18 Verdantas Inc., which fell 18% to $16 million in billings last year.
“Rising construction costs and high interest rates continue to impact project budgets and workforce availability,” Aecom’s Southern California regional executive Joseph Quitter said.
“At the same time, increasing demand from electrification, AI, and data centers is placing added pressure on grid capacity, workforce development, and project delivery,” Senior Vice President Quitter added.
A Verdantas representative said that while individual office billings decreased, the company overall grew billings statewide and nationwide driven by several acquisitions last year.
Tetra Tech, No. 4 with $115.8 million in OC billings, noted the firm has seen “strong sales” in the water sector, including PFAS and advance water purification design.
Kimley-Horn and Associates Inc., based in Raleigh, North Carolina, with an office in Orange, opened a second local office in the city of Irvine this year. The firm, at No. 7, reported OC billings of $64 million for 2025.
“This strategic expansion will allow us to better serve clients throughout the region particularly in south county while deepening our local expertise and enhancing our ability to deliver high-quality consulting services,” Vice President Jason Marechal told the Business Journal.