Hillsborough County's water and wastewater utility now holds the highest possible credit rating from all three major agencies, a move that will lower borrowing costs on the county's largest-ever financing deal.

The county announced Wednesday, Aug. 26, that S&P Global Ratings upgraded the Water and Wastewater System from AA+ to AAA with a stable outlook. Moody's Investors Service and Fitch Ratings already rated the system at the top mark. The triple-AAA distinction means the county can borrow at the most favorable interest rates available to any municipal issuer.

The timing matters for Apollo Beach and Ruskin residents. The county is preparing to sell up to $700 million in long-term utility revenue bonds to fund construction of the One Water Campus, a new wastewater treatment complex being built on roughly 200 acres near the Southeast County Landfill in Lithia. The bond sale will be the largest financing transaction in county history.

Those bonds will be repaid through the utility system's revenues, not property taxes, according to The Southshore Circle.

What the One Water Campus means for South Shore

The One Water Campus is the centerpiece of a $1.6 billion program serving the county's South-Central Service Area, which includes Apollo Beach, Ruskin, Riverview, Wimauma, Gibsonton, Brandon, Sun City and Valrico.

The existing South County wastewater plant had a permitted capacity of 10 million gallons per day. A 2019 county engineering analysis projected it could reach that limit between 2025 and 2027. As The Southshore Circle reported in July, the new campus will include an advanced wastewater treatment facility with an eventual capacity of 30 million gallons per day, the Balm Road Super Pump Station capable of moving 56 million gallons daily, and more than 20 miles of new pipeline. The treatment plant is expected to open in phases, with permanent operations not beginning until 2028.

S&P cited three factors in the upgrade: the county's investment in expanding the water and wastewater system, the accuracy of its budgeting process, and a growing customer base. Hillsborough County is projected to add more than 530,000 residents by 2050, with South and East Hillsborough absorbing much of that growth.

County Commissioner Christine Miller acknowledged the infrastructure gap at the One Water Campus groundbreaking on Friday, April 24, telling The Southshore Circle, "development continued while the supporting infrastructure lagged behind."

The county now holds AAA ratings on two types of credit: utility revenue bonds and general obligation bonds. No specific date for the $700 million bond sale has been announced.