Tampa Bay Water approves South Hillsborough well field, cuts scope of brackish‑water desalination study

Tampa Bay Water’s board on Monday voted to advance the South Hillsborough Well Field as an early implementation water supply while reducing the scope of a feasibility study into expanding the seawater desalination plant with brackish groundwater.

The board approved a single motion to reduce the desalination expansion study and to designate the South Hills Well Field as a new water‑supply and treatment capacity project. The vote was unanimous.

The well field could produce between about 3 million and 12 million gallons per day (MGD) depending on final permit quantities and potential purchase of groundwater credits from Hillsborough County’s South Hillsborough Aquifer Recharge Program (SHARP). Staff told the board the full build would include eight production wells (one is already built), roughly four miles of collector main, a new point of connection and metering facilities adjacent to a Hillsborough County drinking water facility.

Estimated capital costs presented to the board range from $126.2 million to $166.5 million depending on treatment capacity selected. Staff estimated the project’s impact on Tampa Bay Water’s uniform rate to be roughly 8 to 11 cents per thousand gallons, depending on final design and financing choices.

Staff said the well field’s groundwater quality is good and would require only ozone treatment for hydrogen sulfide removal. The project can be phased as permits and credits are obtained; staff emphasized it is near the service area with co‑location benefits next to county infrastructure.

Danielle Kersey, senior project manager, and Maribel Medina, planning and projects director, explained that there are insufficient SHARP groundwater credits available to simultaneously provide the net environmental benefit required for both the desalination brackish expansion and the South Hills well field. Because the brackish expansion would be substantially more expensive (presented capital estimate of about $583 million for the brackish option versus $624 million for seawater expansion), and because a competing project could yield similar quantities sooner and at lower cost, staff proposed reducing the brackish expansion study scope now and keeping the seawater expansion option on the longer‑term list.

Medina told the board the agency already holds at least 3 MGD of permitted capacity via acquired permits from private landowners and could increase yield by about 6.1 MGD through purchases of SHARP credits based on the county’s minimum recharge assumptions.

Medina also described a proposed interlocal property exchange with Hillsborough County’s environmental lands acquisition program (ELAP): the agency could obtain five acres on ELAP’s Stacy R. White Nature Preserve at no cost in exchange for development rights at the former Cone Ranch site. Board members were told the Cone Ranch site would be uneconomic to develop (staff analysis estimated roughly $30 million to obtain only 100,000 gallons per day there) and that the proposed exchange is cost‑effective for the region.

Councilwoman Hanowitz moved approval and Councilman Miranda seconded. Board members asked about outstanding negotiations with Hillsborough County on the cost and term of SHARP credits; staff said they have agreed on a 30‑year term and are now negotiating credit pricing.

Staff characterized the action as positioning Tampa Bay Water to supply rapidly growing parts of south Hillsborough County at comparatively low cost, while deferring a higher‑cost desalination alternative until net‑benefit credit availability changes.

If board members approve the next steps, staff plans to return with land easement agreements and additional implementation items in coming months.