Lake Iamonia is a 5,757 acre lake at 98.6 ft above mean sea level, located in the Tallahassee Hills Region of Leon County, 12 miles north of Tallahassee and 2.5 miles south of the Georgia border. Lake Iamonia is seven miles long and up to two miles wide. It is shallow, with an average depth of less than 5 feet. When the lake water level falls to 95 feet above mean sea level, 72 percent of the lake bottom is uncovered (Young and Crew, 1978).

The volume of water in the lake is not only affected by water in its own drainage basin, but it also receives water from the Ochlockonee River to the west and is affected by rainfall in southwestern Georgia. Lake Iamonia, on its eastern edge near Thomasville Road is quite clean. It is borderline oligotrophic, which makes it one of the cleanest lakes in Leon County. However, the western edge, closest to the Ochlockonee River, is borderline eutrophic. This is direct evidence of the influence ofdegraded water from the Ochlockonee River on Lake Iamonia. Under conditions of normal rainfall, about twice a year the Ochlockonee spills into Lake Iamonia through a series of sloughs at the western end of the lake.

The preferred water level in Lake Iamonia is subjected to a constant state of debate. In times past, the lake bottom was used for agricultural purposes. A dam was built in 1910 to keep Ochlockonee River water out so that what little water remained in the lake would drain down the sink (Sellards, 1914). Ultimately, the sloughs connecting Iamonia were restricted to limited flows beneath two small bridges under Meridian Road to the west.

In 1940, an earthen dike and a concrete spillway were constructed to isolate the sink basin and stabilize water levels in the lake. Sometime before 1950, earthen dikes were built across Cromartie and Strickland arms to maintain water within those basins, too. Once water levels stabilized, aquatic plants proliferated throughout Lake Iamonia, especially Cromartie and Strickland Arms. By the 1970's attempts were made to allow the lake to draw down. In 1978, the Florida Game and Fresh Water Fish Commission built draw down structures under both Meridian Road bridges and the Sink Basin (Wagner and Musgrove, 1983). The weirs and gates built to control the flow of the Ochlockonee into Lake Iamonia failed repeatedly and most were removed by 1980. The 60-inch metal pipes with sluice gates built into the earthen dikes at the sink basin were still operational when the lake went dry in August 2000. At that time an inspection of the structure resulted in condemnation by the Northwest Florida Water Management District due to extensive cypress growth along the berm. The structure is too unstable to keep water out of the sink during high water and the two sluice gates on the control structure are now welded open.

The Sink basin, located on the northern shore of Lake Iamonia, has a surface area of 19.52 acres at 95 ft, and a maximum depth of 40 feet. The control structure has been open, yet the lake remained full and only began to drop in late 2003. Continued doubt that the sink was not taking water and that declining lake levels were due to evapotranspiration led to an experimental closing of the gates to the Sink basin in May 2000. The water level in the Sink basin rapidly declined, evidence that the sink was actively taking water.

Lake Iamonia went dry during the drought of 1999-2000. The deep central valley in Lake Iamonia remained full of water due to a berm in the control structure leading to the sinkhole, which kept water out of the sink. This was thought to allow fish populations to survive so that the lake would not need restocking.

Historically, winter storms have caused the Ochlockonee River to rise and flood into Lake Iamonia. During a storm in March 2001, the lake rose enough to wet the bases of the cypress trees, but continuing drought conditions caused the lake to gradually drain again. In November of 2002, another winter storm resulted in the lake rising 2.3 feet over a four-day period. By the end of March 2003, several winter storms caused the Ochlockonee to flood into Lake Iamonia. On February 16, 2003, weather systems dropped 1.28" of rain; on February 27, 2003, another 3.45" fell; on March 1, 2003, 2.04 inches; and on March 9, 2003, another 3.21" of rain. After these storms, Lake Iamonia was completely full of water for the first time since 1999. Fishermen came back to find the lake full of juvenile fish.

The influx of high nutrient river water was almost immediately translated into luxuriant aquatic plant growth. Many of the floating islands that had been obstructing the western reaches of Lake Iamonia near the Ochlockonee River were blown into the open waters on the eastern side of the lake. Also, during these rains, a number of septic tanks in the Killearn Lakes subdivision failed. Lester Creek, which drains the western portion of the Killearn Chain of Lakes, contributes pollutants to Lake Iamonia and serious algal blooms have occurred in Lester Cove.

Lake Iamonia is a beautiful Leon County lake that has suffered decades of nutrient enrichment from the Ochlockonee River. As development encroaches into its drainage basin most homes rely on septic system for wastewater disposal. The soils in this area of the Tallahassee Hills are poorly suited for septic systems because the clays do not percolate well. Though septic systems may last indefinitely, without regular maintenance, septic systems are prone to failure. Precautions should be taken to protect Lake Iamonia from unnecessary contamination due to improperly preforming septic systems.