Lower Green Bay and the Fox River have been deemed an "Area of Concern" (AOC) by the International Joint Commission (IJC) and the Wisconsin Department of Natural Resources.  The area has been designated an AOC because many of the beneficial uses are restricted or impaired due to the degradation of habitat and the persistence of pollutants.  The AOC is comprised of the section of the Fox River below the De Pere dam to the mouth of the river and the area of Green Bay from the mouth of the Fox River north to Long Tail Point and Point au Sable.

Many of the beneficial use restrictions listed for Green Bay and the Fox River are due to hypereutrophic conditions.  Hypereutrophic conditions result from excess runoff of nutrients and sediment which are characterized by frequent and severe nuisance algal blooms and low water clarity.  Hypereutrophic waters typically have a transparency of less than 3 feet in depth, chlorophyll a concentrations greater than 40 ug/L, and total phosphorus concentrations greater than 0.1 mg/L.  Also, excessive algal blooms can significantly reduce oxygen levels in the water column and impact the growth of submerged aquatic vegetation.

In 1988, a Remedial Action Plan (RAP) was developed for the lower Bay of Green Bay and the Fox River.  The RAP made specific recommendations on how to restore beneficial uses to the AOC. 

In order to restore beneficial uses and possible reverse degradation, the RAP set specific target concentrations for phosphorus, total suspended solids and chlorophyll a.  The objective was to achieve sufficient water clarity to meet the state swimming standard of 1.3 meters (meters).  It was also determined that if water clarity could improve to at least .7 m, populations of submerged aquatic vegetation could survive in the AOC.

Unfortunately, at this time, the AOC is not meeting any of the RAP targets. 

Impairments to the AOC

Impairment	Cause
Fish consumption advisories	Toxic substances, PCBs
Degradation of fish and wildlife populations	Excess phosphorus and suspended sediments
Bird and animal deformities	Toxic substances, PCBs
Degradation of sediment	Toxic substances, PCBs, excess phosphorus, and suspended sediments
Restriction on dredging	Toxic substances, PCBs
Eutrophication	Excess phosphorus and suspended sediments
Drinking water restrictions due to taste and odor problems	Toxic substances
Beach closings	Bacteria
Degradation of phytoplankton and zooplankton populations	Phosphorus and toxic substances
Loss of fish and wildlife habitat	Excess phosphorus and suspended sediments

Table from UW-Sea Grant Institution, State of the Bay 2006