This study was conducted on sediment and overlying water samples from Mogan Lake, an important recreational area, in April, July and October 2015 and January 2016. The noteworthy data for this study were presented as follows: a) Sediment adsorption/desorption characteristics dependent on phosphate concentration, temperature and time were determined using models, and the relevant parameters were derived. b) Sediment equilibrium phosphate concentrations (EPC0) and the critical dissolved phosphorus in the overlyingwater were estimated. Presentation of the research data is as follows: a) Phosphorous adsorption in the sediment samples was theoretically between 421 mgP kg(-1) and 1,001 mgP kg(-1), and phosphorus sorption efficiency was estimated at 0.21-1.92 L mg(-1). Based on the Langmuir Model, the mean maximum adsorption capacity obtained for the July samples was significantly higher than that obtained for October (p < 0.05). Moreover, regarding the very low degree of sediment phosphorus desorption (<1%), it can be concluded that sediment does not behave as a desorbant material for phosphorus. b) Considering the EPC0 values (5.5 x 10(-3) and 46.6 x 10(-3) mg L-1), when the overlying water SRP concentrations fall below 0.008 mg L-1 in October and 0.046 mg L-1 in July, there will be a risk of phosphorus flux from the sediment to the lake water. Considering the overlying water SRP values reported for Lake Mogan, monitoring them in the months of October and July will prove to be decisive in predicting the internal phosphorus load of the lake.