An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Great Lakes AOCs

Beneficial Use Impairments for the Great Lakes AOCs

BUI Coordinator

Leah Medley

What are Beneficial Use Impairments (BUIs)?

An impairment of beneficial uses means a change in the chemical, physical or biological integrity of the Great Lakes system sufficient to cause significant environmental degradation. The International Joint Commission identified 14 BUIs listed below. All BUIs that have been designated for an AOC, must be removed for the AOC to be considered restored and begin the delisting process. To learn more about actions taken to remove BUIs, see Restoring the Great Lakes AOCs.

For more information on each BUI, see  BUI Descriptions.  

  1. Restrictions on Fish and Wildlife Consumption
  2. Tainting of Fish and Wildlife Flavor
  3. Degradation of Fish and Wildlife Populations
  4. Fish Tumors or Other Deformities
  5. Bird or Animal Deformities or Reproduction Problems
  6. Degradation of Benthos
  7. Restrictions on Dredging Activities
  8. Eutrophication or Undesirable Algae
  9. Restrictions on Drinking Water Consumption or Taste and Odor Problems
  10. Beach Closings
  11. Degradation of Aesthetics
  12. Added Costs to Agriculture or Industry
  13. Degradation of Phytoplankton and Zooplankton Populations
  14. Loss of Fish and Wildlife Habitat

Removing BUIs is Based on Local Restoration Targets

In order to address BUIs, each state and local advisory group created restoration targets that define success for each BUI. EPA and other federal agencies did not define explicit targets for each BUI. The International Joint Commission provided some very broad guidance on targets for each BUI in the early 1990s. However, an EPA guidance document offered these criteria for restoration targets:

diagram showing steps toward removing beneficial use impairments

  • Targets should be premised on local goals and related objectives for the watershed; they should be consistent with applicable federal and state regulations, objectives, guidelines, standards and policies, when available, and the principles and objectives embodied in the AOC Annex 1 in the 2012 Great Lakes Water Quality Agreement.
  • Targets should have measurable indicators and also be realistic and achievable.
  • Targets should be developed and periodically reviewed on a site-specific basis (allowing for flexibility in addressing local conditions) by the respective state agencies in consultation with local stakeholders and other interested parties.  This is important because as new information is developed, the states and local communities are encouraged to modify targets to effectively remove the BUIs.