Green Bay is the largest freshwater estuary in the world. All the waters within the Lower Fox River Basin drain to Green Bay. However, there are waters within the Lower Fox River Basin that are impaired due to high levels of sediment and phosphorus entering the waters. Impaired waters need to be corrected – – restored to fishable, swimmable, and designated use conditions as required by the U.S. EPA in the Clean Water Act.
All land uses within the Lower Fox River Basin, whether urban or rural, contribute a source of sediment and phosphorus to the waters within the basin to some extent, but in varying amounts. To determine the amounts of sediment and phosphorus being delivered to the waters, total maximum daily loads (TMDLs) were developed and subsequently approved by EPA in May 2012 (http://dnr.wi.gov/topic/tmdls/). By knowing the amounts of sediment and phosphorus being delivered to a waterbody, and which areas or land uses contribute the most pollutants, resource managers can focus their restoration efforts in the watershed in order to achieve improved water quality.