Wettest rainy season on record adds water flow to the Hillsborough River

After a dry rainy season in 2023, Tampa Bay received a whopping 51.87 inches of rain between June and September. This year’s downpour broke the previous record of 51.22 inches, set back in 1945. But how did this dramatic shift happen? Daily afternoon thunderstorms powered by an easterly wind pattern dominated the summer. Unlike last year, when Tampa Bay endured one of its driest rainy seasons in 135 years, this year’s winds collided with the afternoon sea breeze, sparking thunderstorms across the region. Add Tropical Storm Debby to the mix, and the result was record-breaking rainfall.

When Hurricane Milton loomed in early October, the Southwest Florida Water Management District (the District) sprang into action to protect communities from potential flooding. The Tampa Bypass Canal System—a feat of engineering built in response to Hurricane Donna’s devastation in 1960—was activated to keep the Hillsborough River’s waters in check.

As Hurricane Milton approached, the District preemptively closed the S-155 water control structure on the Hillsborough River. This move minimized freshwater discharge into Tampa Bay, reducing the risk of storm surge flooding. Meanwhile, the Hillsborough Flood Detention Area (HFDA)—a vast, empty reservoir—began to fill with floodwaters, preventing excessive flow from reaching Temple Terrace and Tampa.

The stored water was gradually funneled into the Tampa Bypass Canal, a 15.7-mile channel that safely diverts floodwaters to McKay Bay. The Hillsborough River continued to receive runoff from local tributaries like Cypress Creek, but the HFDA played a vital role in preventing catastrophic flooding. For safety, boat barriers were installed around the S-155 structure near I-75, restricting navigation in the area while the system worked to protect thousands of homes.

The Tampa Bypass Canal System isn’t just a flood control hero—it’s also a critical water supply source for the region. Balancing these dual roles is key: too much water risks flooding neighborhoods, while too little impacts the health of the river. Thanks to the Tampa Bypass Canal System, the Hillsborough River once again proved its resilience. As the HFDA filled and floodwaters were diverted, Tampa and Temple Terrace were shielded from the worst of Hurricane Milton’s wrath.

This season served as a powerful reminder of the Hillsborough River’s value—not just as a natural resource, but as a lifeline for the communities it flows through. With smart planning and infrastructure, the river remains a protector, providing both safety and sustenance for the Tampa Bay area.