Geologic HistoryTo understand the uniqueness of Crooked Lake, first we must understand how it was formed.
Most of peninusular Florida, including Crooked Lake, is underlain by thousands of feet of limestone, dolomite, and similar sedimentary rocks.
Beginning approximately 65 million years ago, what is now peninsular Florida was covered by a warm shallow sea (similar to the current Bahama banks). These shallow sea conditions allowed for the growth of corals and other sea creatures with exoskeletons comprised primarily calcium carbonate. This large coral platform was seperated from the North American Continent by a trough in the sea floor, which limited the amount of sand and other continental debris from accumulating on the platform. Over millions of years, thousands of feet of limestone would accumulate with relatively little influence from the rest of the North American Continent. These limestones comprise what is currently known as the Floridan Aquifer System.
Approximately 20 million years ago, a shift in the ocean currents resulted in upwelling of colder water and sediments from greater depths. The fine grained sands and clays, including high concentrations of phosphate minerals, were deposited on top of the older limestones. These deposits are known as part of the Hawthorn Group of sediments, and serve as a confining unit between the Floridan Aquifer System and shallower unconsolidated sediments.
Around this time, tectonic activity caused the Appalachian Mountains to rise, which led to more erosion and the trough between peninsular Florida and continental North American was filled with sediment, changing the ocean currents to flow around peninsular Florida. This resulted sediments from continental North America accumulating on top of the Hawthorn Group.
Until approximately 1.8 million years ago, the sea level had typically been substantially higher than current levels. Since that time, sea levels have fluctuated above and below current levels. This part of history is commonly known as the Glacial Period (formally known as the Pleistocene Epoch), with periodic advancing and retreating of Artic and Antartic ice caps. With the advancing and retreating ice caps, global sea levels fell and rose. During this time period, Florida's shoreline advanced and retreated hundreds of miles from its current location.
During periods of glacial retreat, when ocean levels were high, highland areas of central Florida became near-shore environments, including ocean dune systems and in some cases, isolated islands. The Lake Wales Ridge is an example of an ancient near-shore environment.
Since the last glacial retreat (and sea level high), Florida's topography has been shaped primarily by rainfall and its interaction with underground rocks and sediments. Central Florida's geology of unconsolidated sediments underlain by thin layers of clay and limestone has resulted in a concentration of sinkhole lakes. Limestone rocks dissolve away when exposed to acids. Rainfall is slightly acidic - due to a small concentration of carbonic acid from the dissolution of carbon dioxide from the atmosphere. Over thousands of years, preferential flow paths in the limestone rocks and the slightly acidic rainwater can result in large cavities in the rock. The clay layer over the cavity can mask it's formation until the clay collapses in a catostrophic fashion. Crooked Lake was likely formed by multiple sinkhole collapses in close proximity over the last 5-10,000 years.
- Lane, Ed. Florida's Geological History and Geological Resources. 1994. Florida Geological Survey
- U.S. Geological Survey. Geologic Controls on the Formation of Florida Sinkhole Lakes. 2000. Open-File Report 00-294
Modern HistoryLocal Residents have Enjoyed, and impacted, Crooked Lake for over a Century
Crooked Lake is located within a closed basin. Except for very infrequent discharges south to Lake Clinch, surface water does not flow into our out of the Crooked Lake watershed. Therefore, the biggest influences on water levels and water quality are the activities within the watershed.
The earliest maps of Central Florida label present day Crooked Lake as Lake Okhakonkonhee. This is thought to be derived from the Creek Native American words Akhauke (mudhole) and Kunki (crooked) - a crooked lake with many mudholes. The first map with Crooked Lake, as it's currently known, was published in 1888.
The eastern and northern shores of Crooked Lake are banked by steep rises in elevation, in some places more than 180 feet above the lake. The western and southern shores, however, are banked by lowlands that can be inundated when water levels rise. This led to several confrontations between groups of early settlers in the late 19th and early 20th centuries. Ranchers and farmers on the western and southern shores of Crooked Lake began digging ditches to drain the lowlands as early as the 1880s. This includes an outfall ditch that drains Crooked Lake south to Lake Clinch when water levels get high.
In 1922, property owners at the southern end of the lake widened and deepened the outfall ditch, which caused a precipitous drop in the lake level. A group of residents immediately obtained a court injunction to prevent the lowering of the lake. They also purchased land along the ditch and built an obstruction to stop the flow of water. Reportedly, the canal was cleared and obstructed multiple times over the first half of the 20th century.
In the middle of the 20th century, a permanent control structure was built in the ditch. The concrete weir was constructed with a top elevation of 120.0 feet NGVD 1929. Stop logs can be added to the weir to increase the elevation by approximatley 2 feet. The control structure and most of the drainage ditch are located on private property. As such, the drainage ditch and control structure are not regularly maintained.
Following the hurricane season in late 2004, water levels in Crooked Lake rose substantially above the control weir elevation. This resulted in flooding of low-lying structures along the lake. Flow through the drainage ditch was slowed substantially due to vegetation growth and erosion in and around the ditch. Following complaints from local residents with low-lying properties, the Polk County Board of County Commissioners performed emergency maintenance on the ditch, clearing vegetation and restoring flow, which quickly brought lake levels down.
- Quinn, Louise. Crooked Lake-Babson Park Rediscovered. 1990
- Knetsch, Joe. Hamilton Disston and the Development of Florida. 2018. Sunland Tribune.
- The Florida Agriculturist. (DeLand, Fla.), 05 Nov. 1890. Chronicling America: Historic American Newspapers. Lib. of Congress.
The following timeline highlight the major activities in the modern history of the Crooked Lake Watershed.