Constructed wetlands offer an effective nutrient removal mechanism while also providing an ideal environment for the growth of grasses similar to those currently being considered as feedstocks for ethanol production. In the present work, a hypothetical wetland system is designed to treat non-point source nutrient loadings and produce harvestable biomass. Through the integration of a biomass production model, a nutrient removal model and a cost model, the relationship between the costs of wetland construction, benefits from biomass sales, and mass nutrient removal can be seen for various wetland sizes and water throughput capacities. Several cost scenarios were simulated and the wetland showed a profit only when construction, operation and maintenance costs were excluded from the analysis. From a cost efficiency standpoint, there exists an optimal wetland size and pumping capacity for the hypothetical site near Camargo, Illinois which is assumed to draw water from the Embarras River. A 34 ha wetland with a 2.3 m3/s design pumping capacity was found to have the maximum cost efficiency with a cost of 4.8 $/kg of NO3-N removed.