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Nutrient Loading and Regional Water Bodies — Great Lakes and the Gulf of Mexico. Thomas W. Easterly, P.E., BCEE, QEP Commissioner IN Department of Environmental Management. Mississippi Watershed Only States. Alabama Arkansas Colorado Georgia Iowa Kansas Kentucky Louisiana Missouri
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Nutrient Loading and Regional Water Bodies—Great Lakes and the Gulf of Mexico Thomas W. Easterly, P.E., BCEE, QEP Commissioner IN Department of Environmental Management We Protect Hoosiers and Our Environment
Mississippi Watershed Only States Alabama Arkansas Colorado Georgia Iowa Kansas Kentucky Louisiana Missouri Mississippi Montana Nebraska New Mexico North Carolina North Dakota Oklahoma South Dakota Tennessee Texas Virginia West Virginia Wyoming We Protect Hoosiers and Our Environment
Illinois Indiana Michigan Minnesota New York Ohio Pennsylvania Wisconsin States in both the Mississippi and Great Lakes Watersheds We Protect Hoosiers and Our Environment
Symptoms of Eutrophication • High Levels of Chlorophyll • Increases in Epiphytic Algae—algae that grow on the surface of plants • Macroalgae (seaweed) Blooms • Low Dissolved Oxygen • Loss of Submerged Aquatic Vegetation • Algal Blooms We Protect Hoosiers and Our Environment
Lake Erie Environmental History • Eutrophication of Lake Erie was evident by the 1960s leading to the popular conclusion that “Lake Erie is Dead” • States and Provinces imposed limitations on point source phosphorous discharges in the Great Lakes basin and in the 1980s Lake Erie rebounded • Recently indications of eutrophication have returned to Lakes Erie, Michigan, and Ontario; but known phosphorous discharges have remained stable We Protect Hoosiers and Our Environment
Increased Phosphorous Discharges or New Pathways of Internal Cycling? External Loading Before Zebra Mussels Buried We Protect Hoosiers and Our Environment
External loading Nearshore Pelagic Benthic Zebra mussels Profundal established Buried Food Web Disruptions Caused by Invaders? “Nearshore shunt model” R. Hecky et al. Univ. of Waterloo We Protect Hoosiers and Our Environment
Current Great Lakes Science • Great Lakes eutrophication is a phosphorous driven issue • Invasive species including zebra mussels have changed the historical phosphorous cycle resulting in significant eutrophication related issues in multiple lakes • The most effective solution may be to continue to reduce phosphorous loadings to the lakes, but we have not set new targets We Protect Hoosiers and Our Environment
Gulf of Mexico Hypoxia • Historically, Gulf hypoxia has been viewed as a nitrogen limited issue • In 2007, the USGS released a report stating that both nitrogen and phosphorous contribute to the issue • The USGS report estimated state level contributions of these chemicals based upon 1992 land use and a constant release per acre that does not account for nutrient management practices We Protect Hoosiers and Our Environment
Previous Estimates of Nitrogen Source Distribution Goolsby, et al We Protect Hoosiers and Our Environment
Challenges Associated with Gulf Hypoxia • Mapping efforts in 2007 delivered a sobering statistic – this summer’s 20,500 square kilometer area ranks among the three largest measured Gulf zones since 1985 • Nonpoint sources of nutrients are major cause of hypoxia in the Gulf, although there are many other contributors • Nonpoint source reduction programs emphasize voluntary actions • State programs focus on local water quality – not the Gulf of Mexico Bottom-Water Dissolved Oxygen Concentrations for July 21-28, 2007 LUMCON We Protect Hoosiers and Our Environment
Nutrient delivery to the Gulf of MexicoMany Midwestern and Eastern watersheds have higher “delivered yields”—USGS 2007 Nitrogen Phosphorus Alexander et al, Environ. Sci. Techn., in press We Protect Hoosiers and Our Environment
Nutrient sources to the Gulf of MexicoNitrogen and phosphorus are affected by different sources and land uses—USGS 2007 Nutrients Delivered to the Gulf Mississippi/Atchafalaya River Basin Alexander et al, Environ. Sci. Techn., in press
Nutrient delivery to the Gulf of MexicoState shares of the total nutrient flux—USGS 2007 Nitrogen Phosphorus Alexander et al, Environ. Sci. Techn., in press We Protect Hoosiers and Our Environment
National Academy of Science Report • Mississippi River Water Quality and the Clean Water Act: Progress, Challenges and Opportunities • http://books.nap.edu/catalog.php?record_id=12051 We Protect Hoosiers and Our Environment
Conclusions/Recommendations We know that there are problems in both regional watersheds, but we have not determined the nutrient loading levels that will “solve” the problem Actions to protect local water quality may not protect these regional watersheds The bulk of the Gulf of Mexico loadings come from wet weather events We Protect Hoosiers and Our Environment
Conclusions/Recommendations We need to determine “safe loading levels” for both of these regional watersheds and then allocate those levels back to the individual tributaries or States as goals or targets We need better wet weather non point source science and management practices Incentives as well as regulations are likely to be part of the solution We Protect Hoosiers and Our Environment
Sources—Ohio River Valley Water Sanitation Commission and the International Joint Commission Tom Easterly 100 N. Senate Ave. IGCN 1301 Indianapolis, IN 46204 (317) 232-8611 Fax (317) 233-6647 firstname.lastname@example.org We Protect Hoosiers and Our Environment