With depth fluctuations, Midnight Pass the focus of routine county surveys, Public Works director says
As part of his July 2 presentation of his proposed 2026 fiscal year budget for the Sarasota County Public Works Department, Spencer Anderson, director of that department, reminded the county commissioners that one of Public Works’ strategic planning priorities for this year was “Keep Midnight Pass Open!” as noted on a slide he showed them.
“We have been successful so far in doing that, thanks to Mother Nature,” Anderson said.
When Hurricane Helene’s storm surge swept onto Siesta Key in late September 2024, the strength of that volume of water reopened the pass on the southern portion of Siesta Key — near Casey Key — that was closed by two property owners in 1983.
Although the pass soon closed, Hurricane Milton’s storm surge the night of Oct. 9, 2024 reopened.
On Sept. 9, Anderson noted during his July 2 remarks, he and his staff plan to present a report to the commissioners regarding proposed steps to maintain the free flow of water through the inlet. Among those options, Anderson continued, is the dredging of the north and south channels.
“It’s relatively stable,” he said of Midnight Pass. Nonetheless, he added, “We’re starting to see a little erosion on the north side of the inlet.”
The Sept. 9 agenda item will entail “a very healthy conversation of how we move forward with keeping Midnight Pass open,” Anderson added, noting that the consultant will be present.
When Commissioner Tom Knight asked for confirmation that the county legally has the right to keep the pass open, County Administrator Jonathan Lewis referenced the Nov. 6, 2024 letter that he sent to the Florida Department of Environmental Protection (FDEP).
Lewis explained that since the storms reopened the waterway, “I have aggressively taken the position it has reopened, and unless the board tells me otherwise … all these steps that Spencer and his team have taken to go forward is to keep it open.”
As the News Leader reported last November, Lewis told the secretary of FDEP, “It is our determination that this new feature meets the definition of an ‘inlet’ per [Section 62B-41.002(10) of the Florida Administrative Code].”
Lewis added in that letter, “[T]he County will keep the inlet open. Management of this inlet per the requirements of [the Administrative Code] will be considered contingent on site conditions and recommendations based on ongoing monitoring and modeling efforts.”
County staff already had implemented a monitoring program “to collect critical data,” Lewis continued, and staff is “developing a hydrodynamic model of the Sarasota Bay system,” including Little Sarasota Bay, Roberts Bay, Big Sarasota Bay and Blackburn Bay, “down to Venice Inlet and offshore areas in the vicinity of inlets. The model is being set up to evaluate the water levels, currents/flows, flushing/exchange within [Little Sarasota Bay] and the adjacent inland waters,” he explained in the letter.
Staff’s weekly surveys of the inlet “have been really helpful to us and our stakeholder groups, to really have good input on decision making and monitoring of the inlet,” Anderson told the commissioners on July 2.
He mentioned the most recent one that he had sent them, which was dated July 1, The Sarasota News Leader learned through a public records request.
Anderson did have a word of warning, so to speak, about using the pass: “Just be careful when you’re going out there at low tide. The ebb shoal is very shallow. I tried going through there [the previous weekend]; it didn’t work out so good,” he said. “The person in front of me got stuck,” Anderson noted, “so I didn’t go that way.”
He advised the commissioners to wait until high tide to try to go through the inlet.
“It rips through there pretty good,” Chair Joe Neunder also pointed out. “That water moves.”
A shift in the area of the greatest depth
In his written, July 1 update about Midnight Pass, Anderson wrote, “Attached is the most recently updated survey of the Midnight Pass inlet throat along with some external data input from the SBEP [Sarasota Bay Estuary Program]. Based on the data,” he continued, “the pass remains in a reasonably stable condition. With the change of longshore current direction during the summer, we see a slight reshaping of the inlet with some initial indications of erosion of north side of the inlet.”
The email chain shows that, early in the afternoon of July 1, Heather Bryen, an environmental specialist with the county, sent county Stormwater Division and other Public Works staff members — along with David Tomasko, executive director of the SBEP — what she called “the fresh surveys taken Monday, June 30,” in Midnight Pass.
Later on July 1, Tomasko, responded to Bryen and the others to whom she had sent the information, and he included several graphics.
“I’ve taken the data and run some basic stats, looking for trends over time in the characteristics being measured,” Tomasko wrote. “Max depth and cross-sectional area are based on numbers recorded here, but the ‘location’ of the deepest depth along the transect (on a north-south axis) is an estimate based on the location of that value on the graph.”
He reported that the location of the deepest depth of the transect “was trending to the north for the first few months, but now has migrated south again, to a location similar to where it was in the late fall to early winter of 2024 …”
He did note, I’ve gone through the pass about half a dozen times, and much of the channel to the east is less than four feet deep …”
Further, Tomasko explained, “I looked at the relationship between cross-sectional area and water depth. Keep in mind that on the water depth axis, values to the right represent shallower depths (i.e., ‘less negative’). This plot suggests that the cross-sectional area decreases, in general, as the depth of the deepest portion of the transect decreases. I’ll leave that to the coastal engineers to interpret, but I guess it means that an increase in depth is not accompanied by a smaller cross-sectional area, which makes sense, as the last few months have shown a trend of the transect getting both deeper and with a broader cross section.”
