LAUSR

Abstract Harmful algal blooms are now a common occurrence around the world in these Anthropocene times because of fertilization of phosphorus and nitrogen for crop and animal production. One of the most dramatic cases in North America is the recent accelerated eutrophication of Lake Erie in the Laurentian Great Lakes. Also, we have lost, by some estimates, 50% of the world’s wetlands in the 20th century and 90% of the wetlands in Ohio USA over the 19th and 20th centuries. We are proposing a serious analysis of an ecological engineering opportunity to restore parts of the former 400,000 ha (1 million acre) Great Black Swamp that was immediately southwest of Lake Erie in Ohio and is now one of the major sources of agricultural phosphorus to western Lake Erie through the Maumee River. Restoring and creating 20,000–40,000 ha (50,000–100,000 acres) or 5–10% of the original wetlands in the Black Swamp to optimize nutrient reduction could reduce phosphorus loading by 480–960 metric tons/year or 18–37% percent of the annual phosphorus loading by the Maumee River to Lake Erie. A thorough investigation of this idea will first require physical (multi-year mesocosm experiments), mathematical, and business models to explore biogeochemical, hydrologic and economic feasibility and reliability. If this presents reasonable results, it would be followed by the creation of a small 400–1000 ha (1000–2500 acre) demonstration treatment wetland in the Black Swamp region to see if wetland performance will scale up as predicted with the mesocosm and mathematical models. Only after a decade of studies at these smaller scale models and a demonstration levels would the full-scale nutrient retention wetlands be implemented in the former Black Swamp. When completed, these treatment wetlands would cover about 10% of the Great Black Swamp region and could remove, with proper ecological engineering design, 40% or more of the phosphorus load from the Maumee River Basin now going into Lake Erie.