Reservoir operations can regulate nutrient fluxes that affect water quality of reservoirs themselves and receiving water bodies. I developed Lake Operation Optimization of Nutrient Exports (LOONE), a Python-based model that incorporates three coupled modules: 1) a water balance module to simulate water level and operations of a reservoir, 2) a water quality module to simulate dynamics of nutrients and Chlorophyll-a in the water column, and 3) an optimization tool to design optimal reservoir releases with the goal of reducing nutrient exports. The model is demonstrated for Lake Okeechobee in Florida, a large subtropical lake which receives and exports excessive amounts of nutrients, while providing water supply, recreation, and flood control for neighboring communities. LOONE was used to design optimal releases into main distributaries of the lake, St. Lucie Canal and Caloosahatchee River which could decrease P loads by 12-33%. This software package could be used by water managers and operators to evaluate different management strategies to help control water quality issues such as high nutrient exports and harmful algal blooms in reservoirs around the world.