Breach may be main culprit of Hurricane Debby flooding in Sarasota

After a more than three-hour workshop to address the flooding brought by Tropical Storm Debby, Sarasota County commissioners arrived at the conclusion that they need at least one more workshop. 

On Jan. 21, commissioners heard from Public Works director Spencer Anderson, independent stormwater engineer Steve Suau and dozens of members of the public, all weighing in on what led to the historic flooding brought by Tropical Storm Debby, and what may be done to prevent similar future catastrophes. 

Most heavily impacted were the Laurel Meadows area east of I-75, the Colonial Oaks and Colonial Gables neighbors west of the interstate, and continuing west into the Pinecraft community. What they all have in common is Phillippi Creek, a basin that drains 57 square miles of some of the most densely populated areas in Sarasota County from the Cow Pen Slough into the bay.

During their presentations, Anderson and Suau told commissioners the flooding was likely caused by a combination of factors, including a discovered breach in the earthen berm that holds excess water in Celery Fields, dumping water into Laurel Meadows. From there, it rushed downstream along Phillippi Creek, breaching its narrow banks until it widens and deepens into a navigable waterway west of Tuttle Avenue.

Anderson and Suau drew the conclusionn that there was too much water moving through the system, even for such a record rainfall. 

But why?

“Steve said there's got to be something wrong. There's too much water here,” Anderson said. “So we went out and identified an area along the berm that is supposed to divide Cow Pen Slough from Phillippi Creek. The only way we could see it is there was grass that was laid flat on the landfill side of the berm.”

With the visual cue that something was amiss with the berm, Anderson’s crew investigated further. “We removed the vegetation and found that there was a low spot in the berm that had appeared to have breached, and there was sediment and other vegetation on the landfill side that supported that,” he said.

In addition to finding the apparent cause of excess water in Phillippi Creek—that and the fact the entire system isn’t designed to handle well in excess of a foot of of rain from a single storm event—many residents who spoke pressed for the creek to be dredged, which last occurred in 2000.

The recency factor

Many residents moved here recently enough to not have experienced past flooding along Phillippi Creek. For others, it’s been a long “dry spell,” as Anderson described it.

“We came across some of our more seasoned residents that have been around for many years, and they recall this occurring many times in the past, but not in the recent past,” he said. “We've had a dry spell, but in the ’80s and ’60s and the ’70s, the folks that we were talking to said this frequently happened back then, but it's been very dry since. We may have gotten a little comfortable without big rainfall events and thinking that all we're doing is all we're going to need to do.”

Debby was a reminder, he added, that was not the case. Both Anderson and Suau said such flooding events appear to occur in roughly 30-year intervals.

Not content to wait another three decades to determine if history will repeat itself again, another workshop is scheduled for March 12 to further discuss additional mitigation practices.

All it takes is money

The fiscal year 2024 operating budget for the county’s Stormwater Environmental Utility was just shy of $27.3 million, which includes administration, stormwater field services, watershed planning and watershed engineering. 

There are eight current capital improvement programs partially funded at $52.5 million. The stormwater infrastructure maintenance program is partially funded at $17.5 million. Surtax 5 funding for fiscal years 2024-2039 is of $57.56 million.

In addition, the utility has identified 114 non-funded water quality and flood mitigation projects with 2022 cost estimates of $285.5 million. Grants are the primary funding source with a county match usually required. 

In fiscal year 2024, the primary source of revenue for the division came from annual Stormwater Environmental Utility non-ad valorem assessments comprised of a fixed base fee and impervious area fee totaling $26.8 million, $3.8 million from the City of Sarasota and the remainder from the county.