Carollo Engineers

Carollo Engineers is an environmental engineering firm focused entirely on water. Founded in 1933, the employee-owned company plans, designs and helps build drinking water, wastewater, reuse and stormwater infrastructure for utilities across the United States. Carollo pairs traditional engineering with construction management and the control-system programming, known as SCADA, that automates modern treatment plants. Placer County Water Agency tapped Carollo to run construction management and SCADA programming for the $210 million Ophir Water Treatment Plant in Auburn, California, a new surface-water facility that will add 10 million gallons a day of capacity. The firm’s water-only focus has made it a fixture on major municipal treatment projects nationwide, from drinking water to advanced purification and reuse.

Carollo Engineers has done one thing since 1933: water. From a single Phoenix office of three engineers, the employee-owned firm has grown past 1,000 staff across roughly 48 offices and now ranks as the largest water-only consulting practice in the United States. That singular focus spans drinking water, wastewater, water reuse, water resources, and stormwater, from planning and design through construction management.

Two capabilities round out the traditional engineering work. Carollo’s EPIC group handles the electrical, instrumentation, and SCADA programming that automates treatment plants, and its research arm develops and field-tests treatment technologies, including PFAS removal. The Walnut Creek office anchors the firm’s Northern California work, and Carollo pairs its design services with the on-site construction management that sees a plant through to startup.