Article by Dr. Sean E. McGlynn
McGlynn Labs, Inc.
Photos by Jess Van Dyke and Michael Hill
Surface Area: 1,825 acres
Drainage basin: 51,000 acres
Location: Coastal Lowlands
The early settlers of Leon County called Lake Lafayette 'Prairie Lake'. This descriptive name tells a lot about how Lake Lafayette originally looked. It was not until nearby lakes were given to French settlers for helping in the American Revolution, as part of the Lafayette Land Grant, that it became Lake Lafayette. In the late 1940's, Lake Lafayette was broken up into a series of smaller lakes (Upper Lafayette, Piney Z, Lower Lafayette and Alford Arm) by the construction of earthen dikes across the basin to keep portions of the lake full of water year around. This began the process we see today in which the lake is transforming into a vegetated marsh. The Lake Lafayette basin is the most intensively developed of the larger lake basins in Leon County, containing most of central and northern Tallahassee. A railroad runs through its entire length. The lakeshore is home to a federal prison, the Leon County Landfill, Talquin Electric's "Meadows at Woodrun" Wastewater Treatment Plant and ever increasing urban development. It is impounded into four hydrologically distinct units, making it the most modified major lake basin in North Florida, and no longer functioning naturally. Today 78% of Lake Lafayette is publicly owned and yet there is little public access.
Fig. 1: Lake Lafayette
(Click to Enlarge)
Lake Lafayette is currently embroiled in a conflict involving the EPA, FDEP, Leon County and the City of Tallahassee over TMDLs. Federal law requires that pollution standards be set for all impaired water bodies. These standards are called Total Maximum Daily Load (TMDL) limits. Lake Lafayette is the first lake in our area to be assigned a TMD and there is much debate over what pollution levels should be set for this lake. Undoubtedly the results of this first TMDL in our area will define the future of Lake Lafayette.
This lake is the remnant of a Pleistocene river delta. During the last Ice Age, as water levels receded and the coast moved farther south, the site became a river valley and eventually a tributary of the St. Marks River. Dissolution processes in the underlying limestone culminated in the formation of a large basin, 8,925 acres, including a major sinkhole, located seven miles west of the St. Marks River in Upper Lake Lafayette just south of the Cody Scarp at the Fallschase development.
According to the late Calvin Jones, State archaeologist, the Lake Lafayette Basin is one of the premier archeological sites in the state. The lake is surrounded by nearly 40 Native American mounds, several of which have been excavated. One of these is on display at the Florida Museum of Natural History. Of special interest are the large midden mounds on Lake Piney Z and the Temple Mounds at Fallschase. Native American settlements are common in the Lafayette Basin. Some significant archeological sites on Lake Lafayette, the Swift Creek Village and the DeSoto Camp (where the first Christmas was celebrated in the New World), have been excavated.
Fig. 2: Aerial Photo of Lake Lafayette in 1937
(Click to Enlarge)
Prior to human intervention the Lafayette Basin functioned as a temporary lake. Water was frequently exchanged between the lake and the St. Marks River through a series of connecting sloughs (located near Chaires Crossroads on Lower Lake Lafayette). Depending on rainfall patterns, water would flow into or out of the lake. During times of drought the slough drained the lake, leaving a large prairie. In periods of normal rainfall, while the lake is full of water, the sinkhole becomes less active. Diminished hydrostatic pressure gradients to the underlying Floridan Aquifer may cause reduced flows which can lead to blockage of the Sink. Previously, during periods of excessive rainfall, water in the Lafayette basin flowed through the Lafayette Sinkhole and the St. Marks River, both functioning as relief valves. The once large, continuous basin was better able to manage floodwaters than the smaller subdivided basins of today, and excess water had more avenues of escape, helping to diminish flooding.
Fig. 3: Aerial Photo of Lake Lafayette in 1954
(Click to Enlarge)
In 1948, the owners of Piney Z Plantation, modified the central portion of Lake Lafayette as a farm pond (and to improve hunting). Two earthen dikes were constructed through the middle of the lake, separating the central portion from the rest of Lake Lafayette. Prior to this Lake Lafayette functioned as one large hydrological unit. To illustrate how often the lake was dry in the years before 1948, the 'Road to the Lake' as it is now referred to in the Chaires community, was called the 'Road to Town'. In fact, Mrs. Jewell Cooksey, who owned the dairy farm where Windham Hills subdivision is located today, recalls 'horse drawn carriage rides' to town on summer afternoons through the dry lake bottom as the 'most common and pleasant route to Tallahassee'. Lightning could start brush fires in the dry lake. Fire would clear out the accumulated vegetation, transforming the tangle of aquatic plants into an open field of Maidencane (Panicum hemitomon). Currently, with Lake Piney Z cordoning off the central portion of Lake Lafayette, the natural flow of water within the Lafayette basin is blocked. Flooding occurs and Chaires Crossroad is often underwater, making it challenging for residents to reach Apalachee Parkway.
Upper Lake Lafayette, where water empties through the Sinkhole, is now hydrologically isolated from the rest of Lake Lafayette. Stormwater enters the basin from Tallahassee's urbanized area through Weems Creek. Dead centurion oaks (Quercus virginiana) that encircle Upper Lake Lafayette indicate the presence of higher water levels. These upland indicators will not survive even periodic inundation. The dead grey branches are a stark reminder of the hydrologic changes plaguing Upper Lake Lafayette.
Fig. 4: New sinkholes constantly form in the lake beds.
(Click to Enlarge)
Separated into four smaller lakes, Lake Lafayette no longer functions naturally. The portion furthest from the St. Marks River, Upper Lake Lafayette, is fed by several urban streams, and drains into a large active sinkhole. This is the only part of Lake Lafayette that contains an active sinkhole. The next portion proceeding west to the St Marks, Lake Piney Z, represents the center of Lake Lafayette. The City of Tallahassee currently maintains this area as a fishing pond managed by the Florida Fish and Wildlife Conservation Commission. The land bordering Lake Piney Z is currently undergoing high-density residential development. The third subdivision of Lake Lafayette, Lower Lake Lafayette, is the only part of Lake Lafayette still connected to the St. Marks River. A mosquito canal flowing under (and frequently over) Chaires Crossroads connects the two waterbodies. The forth and final segmented portion of Lake Lafayette is the Alford Arm, which receives stormwater runoff from as far north as the Killearn Chain of Lakes and adjacent residential communities (Florida Department of Environmental Protection, 1998). State regulators have concluded that the Lafayette system cannot be managed in its present subdivided condition.
Lake Lafayette has been impounded for so long that few people even realize the extent to which this lake has been altered. Lake Piney Z and Lower Lake Lafayette are clogged with aquatic vegetation, making boating impossible. Recent attempts by the Florida Fish and Wildlife Conservation Commission to restore this portion of Lake Lafayette have had some success. The cycle of dry versus wet is necessary to maintain this lake as a navigable waterway. One popular option for Lake Lafayette would be to remove the dikes and 'let nature take its course'. Such an option may be unrealistic, for property owners have come to expect the predictable water levels that the current impoundments provide. Listed species, such as the Wood Stork (Mycteria americana), have also taken up residence in impounded areas near Chaires Cross (Rodgers, 1987). The storks live in gum-cypress-forested wetland where they have the water beneath their nests that they require. Also, Lake Lafayette could be managed like Lake Miccosukee with a control structure around the sinkhole. In this manner the various sections of Lake Lafayette would remain flooded and vested interests would be satisfied. The major difference would be that a drawdown of the entire basin would be possible. Such an event has not occurred in over 50 years. A draw down would effectively control the aquatic vegetation withour excessive cost, and could be managed as a temporary, controlled event. As the basin becomes more developed, it may become more difficult and more expensive to restore Lake Lafayette.
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Upper Lake Lafayette
Surface Area: 300 acres
Drainage basin: 15,000 acres
Location: Coastal Lowlands
As much as 108 million gallons of storm water flows into Upper Lake Lafayette during a normal rainy day in Tallahassee. Lake Lafayette contains an active sinkhole, Lafayette Sink, through which stormwater flows directly into the Floridan Aquifer. Lake Lafayette was the first lake to drain in the drought which began in 1999. Upper Lake Lafayette fills with urban stormwater during the wet season. Stormwater enters Upper Lake Lafayette basin from at least four sources; a highly urbanized 15,000 acre watershed comprising central Tallahassee, Lafayette Creek; a 255-acre City of Tallahassee Park and sports complex, Tom Brown Park; a 194-acre maximum-security prison, the Federal Correctional Institute (FCI); and a 369-acre high-density residential development, Piney Z Plantation (Castellanos and Detscher, 1998; White et al, 1998).
Dissolved Oxygen is near zero at the bottom of the sinkhole and supersaturated at the surface. This is symptomatic of hypereutrophic systems. Total Nitrogen had increasing trends before the drought, but as the drought persisted, water quality in the Lafayette Sinkhole improved because of lessening stormwater inputs. Chlorophyll levels had improved in Upper Lafayette due to the drought.
During periods of normal rainfall, the area around the Lafayette Sink becomes a 300-acre lake, while in dry periods, all of the water in Upper Lake Lafayette drains into the aquifer through fissures, cracks and caverns. Two caverns have been found in the north wall of the sink. They are at 35 ft depth and are large enough to contain a car. The eastern cavern is blocked with muck about 25 feet beyond the cavern entrance. The western cavern is open and accessible to divers though it presents dangerous obstacles in the form of muck traps that make following life lines back to the entrance difficult. This cavern appears to be the conduit through which water flows from the sink into the aquifer.
Lake Piney Z
Surface Area: 195 Acres
Drainage basin: 1,000 acres
Location: Coastal Lowlands
This waterbody was created in the 1940's by the construction of earthen dikes across Lake Lafayette and extending north through the center of the Lake. The intent was to make a permanent pond for duck hunting and fishing. The westernmost dike extends south from the north shore utilizing a promontory consisting of a large native American midden mound. Once the lake was impounded, recreational activities could proceed unimpeded by fluctuating water levels.
However, impoundment causes problems. Natural water level fluctuations inhibit the unrestrained growth of native and exotic plants as they die back during dry periods and are replaced by terrestrial species. Then, during wet periods, the aquatic plant communities are re-established. The cycle continues as wet cycles and dry cycles fluctuate, allowing neither plant community to become established. Fluctuating water levels create open water and increase wildlife potential, improving fishing and hunting. Impoundment creates stagnation, weed choked waterbodies, and poor fishing and hunting habitats.
In the 1990's the north shore of Lake Piney Z was developed. Several residential communities and a public school, Swift Creek Middle School, were constructed on the site of an ancient Native American village. Professional archeologists excavated this site before construction. Aquatic plant problemsresulting from sedimentation during construction became so serious in Lake Piney Z that the City of Tallahassee and the Florida Wildlife Conservation Commission attempted a restoration effort. Piney Z was emptied and the muck was removed from the lake bottom and mounded into fishing fingers and islands. This effectively removed the muck from the lake bottom, but limited wind driven circulation patterns. Since the restoration, aquatic plants such as Pontidaria lanceolata and Nymphoides odorata have become established throughout the Piney Z Lake. Unfortunately a slow re-flood of the lake allowed the emergent vegetation to colonize most of the lake.
Lower Lake Lafayette (Including Alford Arm)
Surface Area: 1230 Acres (calc), Alford Arm, 100 Acres
Drainage basin: 35,000 (calc)
Location: Coastal Lowlands
Prior to 1948, this shallow, swampy portion of Lake Lafayette was predominantly dry grassland, becoming primarily open water in wet periods. During the drier seasons, usually in the fall and winter, the water receded into Lafayette Sink and the dry vegetation browned after the first hard frost. Occasional lightning strikes could ignite fires, which would burn the accumulated aquatic vegetation. The decomposition or oxidation of organic matter is facilitated by water level fluctuations and the resulting periodic exposure of the lake bottom to sunlight and air. Impoundment stabilized the water levels, allowing cypress trees and other aquatic plants to overtake 94% of the lake surface. Water levels in Lower Lake Lafayette have now been stabilized for over 50 years, a dramatic change in the natural hydrocycle.
Gazing upon Lower Lake Lafayette, one almost gets the feeling that there is no water. The surface of the lake is covered with problemmatic floating islands of aquatic vegetation, called tussocks. Basically mats of decaying vegetation, tussocks float up from the lake bottom and are colonized by aquatic grasses, sedges and even small trees. The tussocks then float around the lake driven by the winds. They can trap or crush boats, docks and piers. Children have been rescued as they walked onto tussocks which then blew to the center of the lake. The neighborhood at Windham Hills recently spent $30,000 to remove the tussocks in their area. Soon after removal was completed, a storm blew more tussocks from across the lake.
The Bureau of Aquatic Plant Control at FDEP could launch an extensive tussock removal program in Lower Lake Lafayette if a few obstacles were removed. According to Rule 62C-54.0035(b) "The waterbody must have access to the boating public by way of an established, improved boat ramp or a direct navigable connection to an eligible water body". Unfortunately, there are no established or improved boat ramps on Lower Lake Lafayette. The ramp on the 'Road to the Lake' is simply a clay road which goes underwater. By Rule, the lake must have a public boat ramp to get funding.
In 1965, a mosquito ditch was dug to connect Lower Lake Lafayette with the St. Marks River. There always was a connection, but only at extreme flood stages. This ditch is small and Chaires Crossroad still floods, but the ditch allows for the floodwater to eventually recede.
A listed species, the Wood Stork (Mycteria americana) lives on Lower Lake Lafayette, near Chaires Cross (Rodgers, 1987). The birds live in gum-cypress-forested wetland habitat which provides the water beneath their nests that they prefer. In the Rodgers study, investigators found the mean age of the cypress trees to be 77 years, the oldest dating to 97 years. Florida Fish and Wildlife Conservation Commission own 607 acres of the lake bottom, including the Wood Stork rookery. The colony is relatively protected except during unnatural water level fluctuations caused by the impoundment at Piney Z Lake and the mosquito canal at Chaires Cross.
Water Quality assessments of Lower Lake Lafayette by FDEP in 1998 did not find significant water quality problems associated with the Leon County landfill. However, several studies have found problems associated with the Meadows at Woodrun STP. Excessive nitrogen enrichment has been reported. Ammonia concentrations approaching 5 ppm were reported by FDEP. These exceed 95% of the values found on other Florida lakes. They reported that these water quality problems are caused by seepage form these Sewage treatment Ponds into the Lake (Bureau of Laboratories, 1998).
Conductivity is near background levels in Lower Lake Lafayette. This is good. As the drought progressed, oxygen values increased to levels beneficial to aquatic organisms. With the return of normal water levels in March 2003, lower oxygen levels returned. This is a result of shading by emergent vegetation. Because the lake is overgrown by emergent aquatic vegetation algal growth in the water is suppressed.
Alford Arm is a long narrow finger of Lower Lake Lafayette extending to the north, receiving Stormwater runoff from as far away as Lake McBride in Bradfordville. The railroad causeway, which separates Alford Arm from Lower Lake Lafayette, contains inadequate culverts and impedes the transfer of waters into Lower Lake Lafayette. Farm pond dams divide Alford Arm into 4 separate ponds. The net result of this water level stabilization is again luxuriant aquatic plant growth. This plant growth does effectively clean the stormwater as it filters down the Arm, finally exiting into Lower Lake Lafayette.