Sinkhole Risk in St. Petersburg

St. Petersburg carries some sinkhole risk, as all of Florida does, because the Florida Geological Survey says carbonate rock underlies the entire state and a sinkhole could theoretically form anywhere (Florida Geological Survey).

The survey adds that risk is considerably higher in certain regions, mainly where limestone is close to the surface or where the water table and aquifer layout favor collapse. For St. Petersburg, as for any Florida area, it also says there is no ready reference on sinkhole prediction or risk assessment for an area, and that many insurers rely on regional maps of sinkhole occurrence or on private sinkhole data instead (FGS sinkhole FAQ).

Geology varies across the region around St. Petersburg. A U.S. Geological Survey study of the region says that in the southern coastal areas, where the deeper aquifers are well confined, groundwater moves upward toward the surface aquifer and sinkholes rarely occur, while parts of the northern coast are highly karstified (USGS Circular 1182). The study does not draw that line street by street, so the reported incident counts for Pinellas County, set out below, are the closest local measure.

Pinellas County lists sinkholes among the hazards on its public risk page, warning that a hole can form in minutes or over years and that extended drought or inland flooding could lead to more of them (Pinellas County).

The Florida Geological Survey incident layer holds 12 reports that give St. Petersburg as the owner's city, spread from 1981 to July 2021, and none of them is marked as a verified sinkhole (FGS subsidence data).

Those 12 records appear under three spellings: 7 as ST. PETERSBURG, 3 as St. Petersburg with a trailing space and 2 as St Petersburg (FGS counts by city). The field is the owner's city, not the location of the hole, so a St. Petersburg mailing address can sit on a record for land elsewhere in Pinellas County. Every St. Petersburg record carries a U in the field the layer labels Verified Sinkhole, and the survey says most incidents in the database have not been field-checked and their cause is not verified (FGS subsidence data).

Seven of the 12 St. Petersburg records list a hole no more than 5 feet long. The largest is the 1981 record of a hole 20 feet long, 20 feet wide and 10 feet deep, and the 2001 record lists a feature 10 feet by 30 feet (FGS subsidence data). A separate St. Petersburg Beach record from February 2017 lists a 6 by 6 foot hole with property damage.

The record is thin for a city of St. Petersburg's size because reporting is voluntary. The survey says no law has ever required sinkholes or sinkhole insurance claims to be entered, that most records now come from dispatcher forms filed through the State Watch Office, and that insurance claim records are a small fraction of the total (FGS subsidence incident reports). The newest St. Petersburg entry is dated July 2021, so as of October 2026 the public file has shown no newer city report for more than five years. Last verified: October 15, 2026, on the Florida Geological Survey website.

By report counts, St. Petersburg and Pinellas County see far fewer incidents than inland Tampa Bay: the FGS layer holds 121 Pinellas reports against 618 for Hillsborough County and 345 for Pasco County (FGS county counts).

Inside Pinellas the reports lean toward the north county. Counting every spelling, Tarpon Springs has 17 owner's city records, Palm Harbor 15, St. Petersburg 12, Dunedin 10 and Clearwater 8, and 43 Pinellas records give no city at all (FGS counts by city). Manatee County, south of Pinellas, has 7 (FGS county counts).

A low count is not a clean bill for any St. Petersburg lot. The survey warns that reported incidents cluster where people live and drive and that many holes in fields and forests are never reported, and a USGS map of west-central Florida notes that urban areas often appear to have higher sinkhole occurrence because of good reporting (FGS sinkhole FAQ; USGS Circular 1182).

St. Petersburg's own groundwater pumping is part of the Tampa Bay sinkhole story, because the USGS says the city began pumping groundwater from well fields north of Tampa and that sinkholes occurred with the development of each of the region's well fields (USGS Circular 1182).

The circular explains that coastal towns began abandoning coastal wells as saltwater moved in, and that the city of St. Petersburg began pumping from well fields in a rural area north of Tampa. By 1978 four well fields in Hillsborough, Pasco and Pinellas counties were pumping an average of 69,900 acre-feet per year, and sinkholes occurred with the development of each one: Cosme in 1930, Eldridge-Wilde in 1954, Section 21 in 1963 and South Pasco in 1973 (USGS Circular 1182).

The same study says more new sinkholes form when groundwater levels are low and that regional groundwater declines, drought and loading by heavy equipment during construction can induce them, which matches the Florida Geological Survey list of probable triggers for collapse: drought, earthmoving, blasting, heavy loading, heavy rainfall and heavy pumping. The survey adds that private residential wells in a St. Petersburg neighborhood are typically not enough to lower the water table and cause sinkholes (FGS sinkhole FAQ).

Timing matters for Pinellas homeowners. The survey says activity is greatest when a drought gives way to normal rainfall, because voids that held water fill with air and a large rain can then push the overburden down into them (FGS sinkhole FAQ).

A St. Petersburg homeowner with a new hole should mark and secure it, keep water out of it, stay out of any building with sinking, sagging or cracking walls, and call the property insurance adjuster, as the Florida Geological Survey advises (FGS sinkhole FAQ).

Small holes in a Pinellas yard often need only clean sand or soil; water poured in can enlarge them, and fill should never include trash, chemicals or anything that could decompose into the aquifer. Filling a new sinkhole generally needs no permit, unless it sits in a wetland or would change surface water flows (FGS sinkhole FAQ). The survey also asks owners to report the incident so it is added to the state database (FGS).

Not every sinking spot in St. Petersburg is a sinkhole. The survey lists look-alikes: compressing clay or organic layers, rotting stumps, broken sewer or drain pipes, broken septic tanks, poorly compacted fill after digging and buried trash (FGS). Pinellas County advises having the area assessed by a certified home inspector or foundation specialist and leaving the home if the hole threatens the structure (Pinellas County), while the state survey says licensed home inspectors and insurance adjusters are not trained or qualified to determine whether a sinkhole is present and that a licensed professional geologist is required to determine it (FGS sinkhole FAQ).

A hole in a St. Petersburg street should be cordoned off and marked, reported to law enforcement and passed to the city or county road department for repair; on a private road the repair usually falls to the owner or the property owners association (FGS sinkhole FAQ). The Florida Department of Environmental Protection does not inspect possible sinkholes, but its FGS Sinkhole Helpline at 850-245-2118 gives verbal guidance (Florida Geological Survey).

Every St. Petersburg property policy must cover catastrophic ground cover collapse, but wider sinkhole loss coverage is an option bought for an extra premium, under section 627.706 of the Florida Statutes (Florida Statutes).

The statute sets a high bar for the mandatory coverage: the ground must collapse abruptly, the hole must be clearly visible to the naked eye, the building and its foundation must be structurally damaged, and the structure must be condemned and ordered vacated. Optional sinkhole coverage on a Pinellas home may carry a deductible of 1, 2, 5 or 10 percent of the dwelling limit, and the insurer may limit both coverages to the principal building (s. 627.706, F.S.).

Deadlines matter. A sinkhole claim on a St. Petersburg home is barred unless the insurer gets notice within 2 years after the policyholder knew or reasonably should have known about the loss (s. 627.706, F.S.).

Buyers in St. Petersburg have two records to check. Under section 627.7073, a seller must disclose before closing that a sinkhole claim was paid and whether the full amount went to repairs, and an insurer that paid a sinkhole claim must file the engineer or geologist report and certification with the county clerk of court, which records it; for a St. Petersburg house that is the Pinellas County clerk (s. 627.7073, F.S.; FGS sinkhole FAQ). Insurance questions and complaints go to the Florida Department of Financial Services help line, 1-877-693-5236 (FGS).