When the Corps of Engineers started open lake dumping again in the late 90's, did the phosphorus stirred up from the sediment contribute to the problems were seeing now?
Open lake disposal was actually restarted in 1986 and has been continuing at various levels since that time. Every source of phosphorus contributes to the problem of excessive nutrients and hence the increase in algae including the Harmful Algal Blooms and so it does contribute. However, the magnitude of the contribution has not been agreed upon. The Ohio Phosphorus Task Force Report (April 2010) identifies Toledo Harbor dredging and open lake disposal as a potential source of phosphorus and notes that the Total Phosphorus load for 1.9 million cubic yards per year would be approximately 1669 metric tonnes per year. This can be compared to the recent average annual loading from the Maumee River of 2338 metric tonnes. As previously noted, Ohio EPA’s Section 401 Certification was limited to only 800,000 cubic yards of dredged material for 2010 dredging. The Task Force did not make a recommendation pertaining to open lake disposal. It was noted that there is a “lack of data related specifically to DRP and because the Task Force was focused primarily on assessing the sources/causes of increasing DRP in the rivers, they opted not to make any recommendations in regard to open lake disposal. However, considering the amount of sediment associated phosphorus that has been loaded into the lake for so many years, there could be an improvement to net phosphorus removal from the system if open lake disposal was discontinued.”
Ed Hammett, Ohio Lake Erie Commission