Waterbody: Lake Iamonia low the lake to have more naturally fluctuating wa- ter levels. Water quality monitoring continues to be used to evaluate the long term health of the lake.
As shown in the following pie chart, approximately 14% of land use in the 66,727 acre Lake Iamonia ba- sin is agriculture, rangeland, urban, utilities or trans- portation. Increases in stormwater runoff and wa- terbody nutrient loads can often be attributed to these types of land uses.
Basin: Lake Iamonia
Lake Iamonia is an approximately 5,554 acre, shal- low, flat-bottomed, phosphorus-limited, prairie lake located in northern Leon County. Drastic water level fluctuations occur from discharge to the sinkhole and receiving floodwaters from the Ochlockonee River. The most recent example is the substantial Background inflow from the river during Spring 2013 which re- Healthy, well-balanced lake communities may be filled the lake. Various control structures have been maintained with some level of human activity, but constructed (and ultimately dismantled) in order to attempt to control water level fluctuations. excessive human disturbance may result in water- body degradation. Human stressors may include in- Starting in the early 1900’s, various management creased inputs of nutrients, sediments, and/or other practices, especially water-level stabilization and contaminants from watershed runoff, adverse hy- changes in land use, have led to the overabundance drologic alterations, undesirable removal of habitat of aquatic plants and the accumulation of organic or riparian buffer vegetation, and introduction of sediment in Lake Iamonia which impede recreational nuisance exotic plants and animals. Water quality usage and threaten its fish, wildlife, and ecosystem standards are designed to protect designated uses of integrity. One of the largest modifications occurred the waters of the state (e.g., recreation, aquatic life, in 1939, when an earthen dam was constructed to fish consumption), and exceedances of these stand- isolate the 20-acre sink basin from the lake. Other ards are associated with interference of the desig- modifications continued, with the latest being the nated use. removal of two gates that were formerly used to Methods control water level. Prior to their removal (2007), the gates had remained open since 1980, due to the Surface water and sediment sampling were con- fact that the Northwest Florida Water Management ducted to determine the health of Lake Iamonia and District deemed the dam to be unsafe for impound- met the requirements of the Florida Department of ing water. These latest modifications have been Environmental Protection (FDEP). performed in order to protect the public and to al- Results Table 1. FDEP’s chlorophyll-a, total nitrogen and phosphorus criteria for lakes applied to Lake Iamonia. Due to low water, the numeric nutrient criteria data requirements could not be calculated for years 2011-2012. Dissolved Oxygen (DO) Total Total As Figure 1 shows, Lake Iamonia often did not meet Nitrogen Phosphorus the state DO criteria. This was not unexpected, since Colored Chlorophyll- Threshold Threshold all stations are shallow (usually less than 2.0 meters) Lakes a 20.0 µg/L 1.27-2.23 0.05-0.16 and are normally covered with vegetation, which mg/L mg/L prevents rapid water exchange with the larger area of the lake and limits the air/water gas exchange. 2004 1.7 0.41 0.01 Plant respiration (samples were often taken in the morning hours) and sediment oxygen demand also 2005 3.9 0.48 0.01 contributed to the low DO saturation values. Staff considers this a natural condition for Lake Iamonia. 2006 1.8 0.57 0.02
Fecal Coliforms and Escherichia coli (E. coli) 2007 5.0 0.90 0.02
Lake Iamonia had previously exceeded the Class III 2008 6.1 1.11 0.04 water quality standard for fecal coliforms. Recently, 2009 5.8 0.53 0.02 E. coli standards supplanted fecal coliform standards in Florida. The E. coli water quality limit of > 126 in 2010 5.6 0.69 0.02 10% of samples collected over a 30 day period was not exceeded in 2015 or 2016. 2011- - - - 2012 Fish Consumption Advisory 2013 14.52 0.72 0.04 The Florida Department of Health has issued con- sumption limits for certain fish in Lake Iamonia due 2014 3.26 0.75 0.03 to elevated levels of mercury. 2015 15.4 0.61 0.04 Click here for more information about fish consump- tion advisories in Leon County. 2016 8.8 0.60 0.02
Nutrients While state numeric nutrient criteria were not ex- Due to drought, several stations were inaccessible ceeded during the period of record, the elevated during the sampling period. Sinkhole activity and chlorophyll-a results in 2013 and 2015 should be drought prevented staff from collecting samples in noted. 2012. When viewing tables and figures, the absence of data mean there was not enough data collected Other Parameters (due to lack of water) to fulfill data requirements. Other parameters appeared to be normal for the The nutrient thresholds and results are found in area and no other impairments were noted. Table 1. Due to low water conditions, FDEP data re- quirements for the Numeric Nutrient Criteria could not be met for 2011 through 2012. Floral Assessment Thank you for your interest in maintaining the qual- ity of Leon County’s water resources. Please feel free The Lake Vegetation Index score for Lake Iamonia to contact us if you have any questions. was 61, placing the lake’s vegetative community in the healthy category. Contact and resources for more information
One hundred plant species were found during the www.LeonCountyFL.gov/Water survey. The native species, fragrant water lily Click here to access the results for all water quality (Nymphaea odorata) was the most dominant stations sampled in 2016. species. Other species include red maple (Acer rubrum), maidencane (Panicum hemitomon) and Click here for a map of the watershed – Sample Sites coastal plain willow (Salix caroliana). IA2, IA4, IA6, IA7, IA8 and LI1B.
The exotic Chinese tallow (Sapium sebiferum), Johnny Richardson, Water Resource Scientist hydrilla (Hydrilla verticillata) and water hyacinth (850) 606-1500 (Eichhornia crassipes) are all listed as Category I [email protected] Invasive Exotics by the Florida Exotic Pest Control Council http://www.fleppc.org/ and are a concern in Lake Iamonia. Alligator weed (Alternanthera philoxe- roides), and Chinese wisteria (Wisteria sinensis) were two Category II Invasive Exotics found in the lake. Additionally, the exotic water spangles (Salvinia minima), and burhead sedge (Oxycaryum cubense) were also found in the littoral zone and floating tussocks of the lake.
Click here for more information on the Lake Iamonia LVI.
Click here for more information on common exotic and invasive plants in Leon County wetlands and wa- terbodies.
Conclusions
Based on ongoing sampling, Lake Iamonia met the nutrient thresholds for the East Panhandle Region. DO criteria were not met, but staff considers the low DO results a natural condition. The Lake Vegetation Index score for Lake Iamonia was 61, placing the lake’s vegetative community in the healthy category.
Other parameters appeared normal for the area and no other impairments were noted.
Figure 1. Dissolved Oxygen Percent Saturation results for Lake Iamonia.