The largest public works project ever taken on by Pima County will come in ahead of schedule and under budget.

The Pima County Regional Wastewater Reclamation Department said its Regional Optimization Master Plan is nearing completion, and it came in at $606 million, more than $100 million under budget.

The final required project of the plan was also completed more than a year ahead of schedule.

“The country has a lot of failing wastewater infrastructure.” said Jackson Jenkins, the department's director. "Now here in Pima County, this community, we can boast that we have made a tremendous investment and we now have a significant portion of our wastewater infrastructure in brand-new, state-of the art condition.”

The plan was designed to improve the quality of treated effluent being pumped into the Santa Cruz River, bringing it up to the U.S. Environmental Protection Agency's standards.

The upgrade put in place with the new plan can treat more than 82 million gallons of sewage per day.