There are several nutrient sources for Lake Trafford.  These sources include; nutrients released from the organic sediment on the lake bottom; ground water inflow; non-point surface water sources such as urban runoff and stormwater runoff from the watershed; the Immokalee Water and Sewer District's wastewater treatment plant operation; and atmospheric deposition.  Available water quality data from the lake indicates that over the past 20 years, phosphorous (the commonly recognized nutrient limiting eutrophication) enrichment has increased (Fig. 8) while concentrations of nitrogen appear to have declined somewhat.

    Field studies by Florida Game and Fresh Wter Fish Commission indicate that there are some 8,000,000 cubic yard of decomposing organic debris covering 1500 acres of the lake bottom (Fig. 11). Reddy (1996) estimated phosphorus release rates from organic sediments were between .5 and 3.3 mg m-2  hr-1 based on data from Lake Apopka, a shallow lake in central Florida with similar sediment.  Using a diffusion rate of 1 mg  m-2 day -1, a potential diffusion loading rate of 5.7 kg day -1 of pphosphorous from the organic sediment to the wateer column can be expected.  Assuming an average depth of water of 2 meters and a lake water volume of 11,000,000 m3, the 5.7 kg day -1 diffusion rate translates into a .6 mg L-1 day -1 or 6 mg m-3 day -1 loading rate from substrate diffusion alone.  Phosphorous loading rates exceeding .13g m-2 Year -1 are considered dangerous loading levels (Wetzel 1983).

    Phosphorus loading from ground water also may be a significant nutrient source.  Lake Trafford is a local discharge area for the shallow ground water aquifer (Fig. 14), adapted from Bennett, 1992).  Utilizing shallow ground water flow data derived from Bennett (1992) and Collier County Pollution Control Department ground water quality data, a loading rate from the shallow ground water system to the lake's water column is approximated at 1.6 mg L -1, or 16 mg m -3.  Nutrient loading from surface water sources and precipitation is entirely unknown.