by SC Reporter Emilie Alfino
City of Sanibel Engineer Oisin Dolley, PE, along with Jordan Varble, PE of Johnson Engineering, presented the first real draft of the Surface Water Management Master Plan to City Council on July 30, 2025. To provide a summary, the plan states these facts:
1. The island is essentially a bowl. The system fills and overflows; it doesn’t drain dry. Two interior freshwater basins outflow to Pine Island Sound via weirs, and saltwater intrusion occurs when freshwater decreases. It is necessary to retain as much rainwater as possible to maintain the freshwater wetland ecosystem.
2. Hurricane Ian severely damaged the island’s infrastructure. Culverts, inlets, and swales were buried, leaving the island more vulnerable to riverine flooding.
3. Damage Repairs Post-Hurricane Ian – At least 4,807 culverts, pipe ends, and swales have been added to the map. Hundreds of culverts and swales are in the process of being cleaned/dug out. Funding was provided by a $10 million Florida Department of Environmental Protection stormwater grant.
4. Seventy-five percent of roads on Sanibel are below elevation five feet NAVD 88 (NAVD is a reference system used by surveyors) and mapping low sea level rise projection for 2080 anticipates 20 percent of roadways will be vulnerable. Increasing the minimum roadway elevation to 4.3 feet NAVD 88 would protect all roadways through 2080.
5. Impacts of storm surge are anticipated to worsen. Maintaining freshwater wetlands becomes increasingly difficult.
6. Pay particular attention to the Tradewinds Subdivision drainage, Bailey Road drainage, and areas of West Gulf Drive. A road elevation goal of 4.3 feet NAVD 88 would provide protection through 2080.
7. Weir Policy Evaluation. The primary objective of the City’s Weir Control Policy should be to continue retaining as much fresh water on the island as practicable.
You can find the full report and PowerPoint presentation on the city’s website at www.mysanibel.com.