Deltona weighs $30M regional stormwater diversions to relieve closed basin

Deltona weighs $30M regional stormwater diversions to relieve closed basinTo address severe flooding in the 35-square-mile Teresa Basin, the Florida city is evaluating large-scale pump stations and force mains, though strict nutrient reduction rules for the St. Johns River pose major regulatory and financial hurdles.

Consultant Ardurra Group proposed regional diversions to Deep Creek or Lake Monroe to relieve the hydrologically closed Teresa Basin.

Because the closed basin currently has zero surface water discharge, any new diversion must fully mitigate nitrogen and phosphorus loads to comply with the Middle St. Johns River BMAP.

Capital costs for the pump stations, miles of force main, and treatment reservoirs are estimated to range from $10 million to over $30 million.

The City Commission unanimously directed staff to update the 2019 Stormwater Master Plan to address immediate street-level flooding while regional solutions are negotiated.

Commissioners also approved a $2 million ARPA fund transfer to ensure the Lake Windsor force main project meets federal spending deadlines.

Deltona, Florida, is exploring massive regional stormwater diversions to relieve the Teresa Basin, a 35-square-mile closed hydrological system severely impacted by recent hurricanes. Ben Pernesny, a senior project manager with Ardurra Group, presented the preliminary findings of a multi-year flood control study to the City Commission on August 24, 2026. Pernesny noted that because the basin lacks a natural outfall, the most viable capital improvements involve pumping excess floodwater to adjacent open basins, such as Deep Creek to the east or Lake Monroe to the south. The conceptual projects require large-capacity pump stations, up to five miles of large-diameter force main, and the construction of regional water treatment reservoirs. Pernesny estimated capital costs could range from $10 million to $30 million, alongside high ongoing operations and maintenance expenses. A major complication for the diversion strategy is water quality compliance. The receiving Middle St. Johns River Basin is impaired and governed by a Basin Management Action Plan (BMAP). Because the Teresa Basin is closed, its current surface pollutant load is considered zero. Pernesny warned that any pumped discharge would constitute a new load of nitrogen and phosphorus that must be heavily mitigated, requiring large attenuation ponds to treat the water prior to discharge. However, the diverted stormwater could offer secondary water supply benefits. One proposed force main alignment passes the Deltona East Water Reclamation Facility, creating an opportunity to augment the city's reclaimed water supply during peak demand periods. Commissioners expressed concern over the feasibility of moving water into the St. Johns River without exacerbating downstream flooding, noting that the regional projects will require extensive coordination with the St. Johns River Water Management District and Volusia County. Recognizing the long lead time for regional mega-projects, the Commission unanimously directed staff to update the city's 2019 Stormwater Master Plan. The update, slated to begin in early fiscal year 2027, will focus on localized, street-level conveyance improvements. In separate water infrastructure business, the Commission approved a critical budget amendment transferring approximately $2 million in American Rescue Plan Act (ARPA) funds to the Lake Windsor force main project. City staff noted the transfer was necessary to issue an invitation to bid by October and meet the federal government's December 2026 expenditure deadline. The city also received a $1.25 million state appropriation check for water main replacements, secured with assistance from state legislators.