It is mid-September, and with rain falling nearly every day in Southwest Florida, it may be difficult for many people to believe that we can still be in a drought, but Audubon’s long-term data from Corkscrew Swamp Sanctuary say just that.
How can we still be in a drought?
The Sanctuary has received below-average rainfall for 19 of the past 22 months. Cumulatively, we are 31 inches below our average since November of 2024. To escape drought conditions, we need significantly more rainfall to refill the aquifer and re-saturate the landscape.
How do we measure water at the Sanctuary?
While rainfall measurements come from rain gauges in different parts of the Sanctuary, the water-level staff gauge at the Sanctuary’s North Lettuce Lake provides an excellent snapshot of how rainfall translates to swamp water levels. This gauge is in one of the deepest parts of the cypress slough and is where staff has been recording water levels since the late 1950s.
In recent decades, water levels at this gauge usually fall below the ground toward the end of the winter "dry" season in March or April. Water would typically stay below ground until summer rains begin, signaling the start of the "wet" season, and by early July, the water level rises back above ground.
This year, water started to come back above ground and refilled the Lettuce Lakes in early July – but then rainfall lessened, and water levels fell below ground again. The lakes were dry for a couple of weeks before rainfall returned and water levels finally rose in early September. As of mid-September, our water-level staff gauge tells us that water levels are still a foot lower than where they usually are.
Why is long-term data so important?
Audubon’s long-term data help put this year’s variability into perspective, allowing for comparison between what we’re seeing this year and what has been seen over the past 70 years.
Have we ever experienced something like this before?
It turns out the reduced rainfall we’ve seen in the last two years is quite similar to the drought last seen in 2007-2008, as well as other years before then, in 1989-1990, 1975-1976, and 1963-1965. The lack of rainfall we’re experiencing is something the ecosystem has experienced about every 10-15 years since the Sanctuary opened.
So it’s all about rain then?
Nope! Rain is only part of the story. Evapotranspiration (ET) is the process of water moving from the earth’s surface into the atmosphere through evaporation and plant “breathing.” This is one of the most important aspects of the water cycle in South Florida. Warmer temperatures result in more ET, so the record-breaking spring and summer temperatures we’ve been seeing have been further drying our landscape in a way we haven’t experienced before, and climate models predict this increased ET will continue as the globe warms.
Okay, so it’s all about rain and evapotranspiration?
There’s more! Another factor that makes the current drought worse for Corkscrew Swamp than earlier droughts is that it’s happening in addition to the overdrainage of the swamp that has been the cause of drier conditions since the early 2000s. The combination of low rainfall, high ET, and overdrainage of surface water is what has led to the near record-breaking low water levels in the Sanctuary this summer.
What are the risks of this low water?
We were fortunate to avoid an active wildfire season this year, but the drier conditions have direct negative effects on fish and crayfish populations, which directly impact predators like wading birds and alligators. Sanctuary staff have even seen understory plant communities along the boardwalk change this year in response to the dry conditions.
What happens now?
Luckily for the Wood Storks and cypress trees, it looks like some relief is on the way. In the coming months, we’re expected to see rainier-than-normal conditions thanks to the Super El Niño that has formed over the Pacific Ocean. This rainfall would help us to recharge our wetlands, restocking our water reserves for wildlife and people. While wet conditions this winter would not be good for Wood Stork nesting this year, it could set the stage for a very strong nesting season the following year.
A solution for the Sanctuary’s overdrainage is coming into sight as well, as South Florida Water Management District’s Corkscrew Watershed Initiative wraps up this winter, providing a roadmap for restoration projects to improve dry season water levels in the swamp. Efforts to hold water in our freshwater wetlands will become more important than ever as our landscape and climate continue to change. Wetlands like those here at Corkscrew Swamp Sanctuary and the Corkscrew Regional Ecosystem Watershed are critical for our region’s resilience in the face of climate change and continued population growth in Florida.
