This sinkhole opened up after Hurricane Debby made landfall in Florida’s Big Bend region on August 5, 2024. Image source: Suwannee River Water Management District.
Sinkholes are a natural part of Florida’s landscape, especially in areas where limestone lies close to the surface. If a sinkhole appears on your property, knowing how to respond is key. This article outlines important first steps, available resources, and expert contacts to help you assess the situation and determine what to do.
How do sinkholes form?
Sinkholes form when surface sediments collapse into empty spaces, or cavities, within the limestone bedrock beneath the ground. These cavities develop over time as slightly acidic groundwater slowly dissolves the limestone. When a cavity becomes too large to support the weight of the ground above it, a sudden collapse can occur, creating a noticeable hole at the surface. In some cases, sinkholes can form gradually as sediments slowly settle into cavities over long periods of time, resulting in shallow, bowl-shaped depressions without a sudden collapse.
Limestone underlies our entire state but there are regions where the risk of sinkholes is higher, such as where the limestone is closer to the surface. Although cavities and voids are a feature of carbonate rocks like limestone, few collapse and directly impact roads or buildings.
Where can you find help if you have a sinkhole on your property?
Sinkhole in Union County, FL. Image source: Suwannee River Water Management District
The Florida Geological Survey (FGS), has a Sinkhole Helpline (850 245-2118) as well as a sinkhole website and extensive Sinkhole FAQ to answer residents’ questions. You can speak with someone on the helpline for guidance about what to do (you may not need to do anything) and they can help clarify information found in the FAQ. The FGS also has a leaflet available, A Homeowner’s Guide to Sinkholes in Florida.
Here are a few important tips to keep in mind, summarized from the Florida Geological Survey Sinkhole FAQ. Much more detailed information is found on the website. Call the sinkhole helpline or your Water Management District for further clarification on steps to take.
Call your local law enforcement agency if there is any risk of physical harm.
For sinkholes under or near structures: Stay out of your house if you suspect the hole is causing or could cause any impact to the structure. In some counties, local government agencies, the sheriff’s office or emergency management office may offer help when a home is endangered.
Contact your property insurance to see if they cover assessment and repair of damage caused to structures. It’s recommended to mark the hole’s approximate boundaries and document its size by taking photographs and monitoring changes. Do this from a safe distance. Keep children and pets away.
For sinkholes in your yard, small holes can often be filled with clean sand or soil.
On large properties, sinkholes that are not actively developing and are not affecting a structure can usually be left alone. If there’s a risk of people or animals falling in, fence or cordon off the sinkhole or you can usually fill the hole with clayey sand (which is preferred) although clean fill material can also be used. Don’t throw anything into a sinkhole or use any fill material that can decompose or leach toxins into groundwater. Call the Sinkhole Helpline for further clarification (850 245-2118).
Although no permit is usually needed to fill a new sinkhole, sinkholes in wetland areas or those that may change water flow or add to groundwater pollution if filled may need an environmental resources permit (ERP) before filling. Contact your Water Management District or FL Department of Environmental Protection (FDEP) District Office for guidance.
Keep in mind that other factors besides sinkholes can cause settling on the land surface. These include decomposing stumps, compressed or decomposing garbage and other debris, collapsed or broken sewer pipes and septic systems, soil that wasn’t compacted properly after excavation was completed, among others.
Coastal wetlands are some of the most ecologically productive environments on Earth. They support diverse plant and animal species, provide essential ecosystem services such as stormwater filtration, and act as buffers against storms. As Helene showed the Big Bend area, storm surge is devastating to these delicate ecosystems.
Hurricane Track on Wednesday evening.
As the force of rushing water erodes soil, uproots vegetation, and reshapes the landscape, critical habitats for wildlife, in and out of the water, is lost, sometimes, forever. Saltwater is forced into the freshwater wetlands. Many plants and aquatic animal species are not adapted to high salinity, and will die off. The ecosystem’s species composition can completely change in just a few short hours.
Prolonged storm surge can overwhelm even the very salt tolerant species. While wetlands are naturally adept at absorbing excess water, the salinity concentration change can lead to complete changes in soil chemistry, sediment build-up, and water oxygen levels. The biodiversity of plant and animal species will change in favor of marine species, versus freshwater species.
Coastal communities impacted by a hurricane change the view of the landscape for months, or even, years. Construction can replace many of the structures lost. Rebuilding wetlands can take hundreds of years. In the meantime, these developments remain even more vulnerable to the effects of the next storm. Apalachicola and Cedar Key are examples of the impacts of storm surge on coastal wetlands. Helene will do even more damage.
Many of the coastal cities in the Big Bend have been implementing mitigation strategies to reduce the damage. Extension agents throughout the area have utilized integrated approaches that combine natural and engineered solutions. Green Stormwater Infrastructure techniques and Living Shorelines are just two approaches being taken.
So, as we all wish them a speedy recovery, take some time to educate yourself on what could be done in all of our Panhandle coastal communities to protect our fragile wetland ecosystems. For more information go to:
The Gulf of Mexico Sea Grant Science Outreach Team is proud to announce four new outreach items that are applicable throughout the US and showcases marine microplastics and homeowners’ insurance:
Marine Microplastics Primer for Extension Professionals – This publication is intended to serve as a guide for extension professionals to aid in answering questions about microplastics that they have encountered or may encounter in the future. The publication can be accessed at https://gulfseagrant.org/wp-content/uploads/2023/08/MASGP-23-051.pdf.
Property Insurance Basics – Confused about homeowners’ insurance and what it covers or know people who are? The outreach team has created a publication to share basic information about insurance to help property owners make informed decisions about the amounts and types of protection for their homes. Access to the publication can be found https://gulfseagrant.org/wp-content/uploads/2023/08/MASGP-23-015.pdf.
What is Risk Rating 2.0 and how will it affect my flood insurance?–FEMA has updated their risk rating approach through a new pricing method. This change is the biggest change to the way flood insurance premiums are calculated since 1968. Want to learn more about this new system and how it will affect your flood insurance? Click https://gulfseagrant.org/wp-content/uploads/2023/08/What-is-Risk-Rating-2.0.pdf to access our publication.
For better or worse, tropical storms are exciting. Besides the energy and tension around the mystery of where a storm will make landfall, the combination of powerful waves coming ashore, intense wind gusts, and driving rain really heighten all the senses. Most long-time Floridians don’t flinch too much at a Category 1 or 2 hurricane. But once we cross the threshold of a Category 3+, things change. If you have lived through a storm like Frederic, Ivan, or Michael, you know the damage and heartache these stronger storms can bring. Even Category 2 storms like Hurricane Sally just three years ago had serious lasting impacts, particularly affecting the under-construction Pensacola Bay Bridge.
An example of damage to local marinas and fishing vessels after Hurricane Michael in 2020. (Photo by Allen Golden).
Post-covid, with the economy (sort of) back in full swing, we are averaging just over 1,200 people a day moving to Florida. From July 2021-July 2022, nearly half a million people arrived, compared to 185,000 in the same timeframe the previous year. While some of these new residents may come from storm-prone locales, many have zero experience with hurricane season on the Gulf. If you are among those new to hurricanes, or know neighbors who could benefit from information, please share these tips with them.
Tip 1: Have the right insurance. The vast majority of insurance companies will not issue new policies when there’s a storm in the Gulf. Officially, hurricane season begins June 1. So, if you don’t have enough coverage for your investments, you should go RIGHT NOW and look into it, before the storm season really heats up in late summer. In addition, different types of policies cover different types of damage. Homeowners’ insurance (fire, theft, etc.) in Florida requires a separate windstorm policy, which includes damage from hurricanes and high winds (always confirm by reading your policy). And these are both separate from flood insurance. Performing certain types of windstorm mitigation, such as wind-rated garages, strong roof to wall connections, and obtaining shutters, can significantly reduce your overall costs for windstorm insurance.
Flood insurance is available through the National Flood Insurance Program (NFIP) and can be reasonably priced for people living outside of a flood zone. Those within designated flood zones will be required to purchase it, and rates vary widely depending on location and any prior flood impacts.
This property experienced significant flooding during a tropical storm a few years ago. Photo credit: Carrie Stevenson, UF IFAS Extension
As for which policy pays for storm impacts, it will become a game of “whodunit” afterwards, with adjustors making determinations of your damage based on the specific characteristics of each storm. These may include the direction of the incoming storm, the windspeed, amount of rain, and where any water damage actually originates from.
Tip 2. Create a disaster kit. Whether you are hunkering down and riding out the storm or getting out of the fray, it’s important to have a disaster kit with certain necessities. I always recommend a waterproof tote bin, to protect important documents from rain or floodwater. Items for a kit include medication, flashlights and batteries, shelf-stable food that can be eaten without heating or refrigeration, gallons of water, pet food, cash (since ATMs won’t work), portable phone chargers, a list of emergency contacts, and insurance paperwork. Comprehensive disaster kit lists can be found at floridadisaster.org. Another benefit of keeping these materials in a portable container is that if you do have to leave your home in a hurry, everything is in one place.
Tip 3. Come up with an evacuation plan. Talk with your immediate and distant family about your plans for a storm. If you plan to evacuate, look at the direction of an incoming storm and find a place to stay that is out of the immediate cone of impact. Sometimes this means moving east or west along the coast; other times it’s best to head inland. It’s important to let others know you’re leaving, in case there are serious impacts to your home from flooding or wind and rescuers are in the neighborhood.
Tip 4. Pay attention to news about predicted storm surge—flooding is the deadliest factor of a hurricane. By using the Florida Division of Emergency Management website to “Know your zone,” you can look up your address to determine whether you are in a potential evacuation zone when a storm comes through.
Evacuation Zones in Florida are color-coded based on risk. Image from floridadisaster.orgA view of the evacuation zones for portions of southern Escambia and Santa Rosa Counties. Image from floridadisaster.org
