This TMDL addresses nutrient impairments in the Tidal Caloosahatchee River. For these nutrient TMDLs, water quality targets were identified using the total nitrogen concentration that reduces algal growth such that there is an adequate percentage of light irradiance in the bottom layer to support a healthy seagrass meadow community in San Carlos Bay. Two computer models (EFDC and HSPF) simulated the Caloosahatchee load under various scenarios to determine the load reductions producing the nutrient reductions necessary to meet the critical light levels for submerged aquatic vegetation in the estuary.