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Hurricane Ian's Rainfall Resulted in Record Water Levels

Rainfall and Water Level Data: September 2022

Graph showing 2022 rainfall through September.
Corkscrew Swamp Sanctuary received 5.8 inches of rainfall over the four days of the storm, bringing the monthly rainfall total to 16 inches. This rainy season (June through September) we’ve seen 47.7 inches of rain fall in the Sanctuary, which is 79% of our average annual rainfall.
Graph showing September rainfall amounts since 1957.
Peak annual water level at Corkscrew Swamp Sanctuary’s B Gauge across the Sanctuary’s 67-year water-level dataset. Hurricane Ian marked the fifth time in Sanctuary history that water peaked above 4 feet, with each record high peak associated with major tropical systems.
Water levels for water year 23 vs historic
Water levels for Water Year 2023 (current year is the red line) compared with annual averages (gray shaded area) dating from 1957 - 2000.
Water levels for water year 23 vs recent decades
Water levels for Water Year 2023 (current year is the red line) compared with annual averages (gray shaded area) compared with annual data since 2000.

Hurricane Ian arrived at the end of a particularly wet September for Southwest Florida, bringing a lot of rain to an ecosystem that was already saturated. Corkscrew Swamp Sanctuary received 5.8 inches of rainfall over the four days of the storm, making 2022 the second rainiest September in the Sanctuary’s 63-year rainfall record.

During the 2022 rainy season  (June through September), 47.7 inches of rain fell in the Sanctuary. This accounts for roughly 79% of our average annual rainfall. Typically, we only receive about 64% of our annual rainfall during these months. 

Rainfall from Hurricane Ian, both in the Sanctuary and upstream in our watershed, led to record water levels at Corkscrew Swamp Sanctuary last week.

The Sanctuary’s “B Gauge,” a staff gauge located along the boardwalk at the North Lettuce Lake, has been collecting water-level data for 67 years and provides the most complete long-term water-level dataset in our area. Water levels at the B Gauge have only exceeded the 4-foot mark five times in the Sanctuary’s history, each time associated with a major tropical event: 1960 with Hurricane Donna, 1995 with Tropical Storm Jerry (followed by Hurricane Opal the same year), 2008 with Tropical Storm Fay, 2017 with Hurricane Irma, and 2022 with Hurricane Ian.

The peak water level following Hurricane Ian (4.18 feet) was remarkably similar to the peak water level seen after Hurricane Irma (4.17 feet) just five years ago, both falling short of the all-time high-water mark of 4.47 feet seen in 1995.
 

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