Elevations within Fort Cooper State Park range from a high of about 82 feet above mean sea level (msl) in the sandhills on the west side of the park to a low of approximately 24 feet msl along the exposed shoreline of Lake Holathlikaha.
Lake Holathlikaha, which is completely contained within Fort Cooper State Park, is the most prominent hydrological feature in the park and its only major surface water body. It is located on the western boundary of the Tsala Apopka Chain of Lakes in eastern Citrus County.
The lake is classified as Outstanding Florida Water and is completely contained within Fort Cooper State Park. Aquatic and semi-aquatic plants occur along most of the shoreline and throughout the basin. Dominant species include sand cord grass, pickerelweed, saw grass, willow, wax myrtle, and cattail. A portion of the northern lakeshore has been cleared and is used as a public beach area. Motorized boats are not permitted on the lake, but canoes and paddleboats rentals are available from a State Park entrance booth. Uplands in the immediate lake basin are covered in natural vegetation and are used primarily for recreation and natural system conservation. Dominant upland species include live oak, hickory, longleaf pine, turkey oak, and saw palmetto. Elevations of saw palmetto at various points throughout the basin provide an indication of high lake-water levels. Water levels are currently monitored at a District gauge site along the northern lakeshore.
Because Fort Cooper Lake is not contiguous with any cypress wetlands, the lake was classified as a Category 3 Lake.
The Tsala Apopka wetlands, including Lake Holathlikaha, are geologic relics of a former ancestral river. The Rainbow River was undoubtedly the head of that ancestral water body, which eventually flowed southward into Tampa Bay through what is currently the Hillsborough River. Existing topographic elevations of the Holathlikaha lakebed clearly reveal a probable southern drainage corridor toward Floral City, as well as a northeastern one toward Davis Lake. However, based on an analysis of existing aerial photography, no functioning surface water connection between these water bodies has existed over the past 75 years.
Four major spring complexes, namely Crystal River, Homosassa, Chassahowitzka, and Weeki Wachee, are located within the Springs Coast Basin. The combined discharge of these four spring groups is 900 million gallons per day. The groundwater basin that supports the spring groups extends across all of Citrus County. Two major aquifer recharge areas in the county are the Brooksville Ridge and the expansive Tsala Apopka wetlands, including Lake Holathlikaha. These areas serve as important groundwater sources for the major coastal springs.
In Citrus County, groundwater flows west from the Withlacoochee River region toward the Gulf of Mexico. Lake Holathlikaha sits atop a portion of the Floridian Aquifer that predominately recharges the Homosassa Springs group; however, the lake is also situated near a groundwater divide between that spring shed and Crystal River Springs group. The Tsala Apopka Chain of Lakes, and thus Lake Holathlikaha, are directly connected to the Floridian Aquifer. They not only receive water from the aquifer but at times also lose water to it.
The documentation of Lake Holathlikaha water levels, recorded by park staff at a South West Florida Water Management District station (#STA 826 20 3110), has been relatively continuous from April 2001 to the present.
Surface water runoff originating outside Fort Cooper State Park is the main cause of decreased water quality in Lake Holathlikaha. Urban development surrounds the park, but the two areas that appear to contribute the greatest amount of contaminated surface water are Old Floral City Road northeast of the park and U.S. Highway 41 immediately west. At one time, water quality at Lake Holathlikaha may have been similar to that of the Tsala Apopka Chain of Lakes
Based on aerial photography from the period of record (1944 through 2011), the open water area of Lake Holathlikaha has fluctuated greatly over time. Water levels of sandhill upland lakes are closely linked with local and regional water table levels. Long-term drought and increased groundwater withdrawals for residential and industrial uses are likely causes of water level declines in the lake. Frequent contractions of the lakeshore encourage the growth of terrestrial vegetation on the exposed lake bottom. When lake levels rise again, however, the terrestrial vegetation is flooded and dies, adding a considerable volume of biomass to the lake. Additionally, at the low stage, the zone of emergent aquatic vegetation extends farther into the lake, only to die during periods of higher water. Consequently, over the years, organics have accumulated in the lake at a high rate. At times, one-fourth to one-third of the original lake surface is obscured by plant growth around the margins. A recent development is the appearance of numerous floating islands consisting of thick mats of organic matter, topped by plants growing to a height of six to eight feet.
Lake Holathlikaha has no boat ramp, but visitors may rent park-owned canoes and paddle boats for use on the lake. Motorized boats have been excluded from the lake since the park was opened to the public in 1977 to reduce the chances of an unintentional introduction of invasive exotic species such as hydrilla and water hyacinth. This prohibition was successful for a number of years in preventing the establishment of exotic plants in the lake confirmed by a June 1991 assessment of the lake. At some point after that, however, park staff discovered that hydrilla had appeared in the lake near the beach area. The park has treated this hydrilla repeatedly and it is no longer apparent. The dominant aquatic species in the lake are two submergents, southern or bushy naiad, and Illinois pondweed. Two other abundant plants are the floating-leaf species, spatterdock, and fragrant white water lily.
Shoreline Lake Holathlikaha is the primary recreational and aesthetic resource of the park. A lakeside picnic area and a beach area provide visitors access to a clear view of the lake.
