Treasures of Oz

Celebrating the Natural Gems of Ozaukee County

  • AOCs, or Areas of Concern, identified in the 1980s as severely degraded geographic areas in the St. Lawrence basin. Defined by the U.S.-Canada Great Lakes Water Quality Agreement (Annex 2 of the 1987 Protocol) as “geographic areas that fail to meet the general or specific objectives of the agreement where such failure has caused or is likely to cause impairment of beneficial use of the area’s ability to support aquatic life.”
  • There are 43 sites total, 26 are entirely in US, 5 are in/bordering Wisconsin.



  • Milwaukee Estuary AOC Beneficial Use Impairments (BUI’s)
    • Loss of fish and wildlife habitat
    • Degradation of fish and wildlife populations
    • Degradation of aesthetics
    • Degradation of benthos
    • Restrictions on fish and wildlife consumption
    • Eutrophication or undesirable algae
    • Beach closings
    • Fish tumors or other deformities
    • Bird or animal deformities or reproduction problems
    • Degradation of phytoplankton and zooplankton populations
    • Restriction on dredging activities
  • This project will help move the Degradation of Fish and Wildlife Populations, Loss of Fish and Wildlife Habitat, and Degradation of Aesthetics Beneficial Use Impairments BUI’s towards delisting goals and criteria.