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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

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
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

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states in both the mississippi and great lakes watersheds
Illinois

Indiana

Michigan

Minnesota

New York

Ohio

Pennsylvania

Wisconsin

States in both the Mississippi and Great Lakes Watersheds

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symptoms of eutrophication
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

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lake erie environmental history
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

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slide8

Increased Phosphorous Discharges or New Pathways of Internal Cycling?

External Loading

Before Zebra

Mussels

Buried

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slide9

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

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current great lakes science
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

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gulf of mexico hypoxia
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

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slide12

Previous Estimates of Nitrogen Source Distribution

Goolsby, et al

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challenges associated with gulf hypoxia
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

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slide14
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

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slide15
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

slide16

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

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national academy of science report
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

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conclusions recommendations
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

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conclusions recommendations19
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

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sources ohio river valley water sanitation commission and the international joint commission
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

teasterly@idem.in.gov

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