Waukesha County, Wisconsin
Proposed for removal from impaired waters during assessment period.
NotesOconomowoc Lake was placed on the impaired waters list for mercury in 1998 and is proposed for removal based on 2001 updated Fish Consumption advisories.
This lake was assessed for phosphorus and algae every two years between 2012 and 2020; no impairment was found.
Impaired Water Notes
This listing was part of a set removed from the impaired waters list due to a change in fish consumption advisory levels in 2001. In 2001 Wisconsin DNR put into effect a statewide fish consumption advisory for mercury due to atmospheric deposition. Most of the lakes removed from the specific fish consumption advisories list in 2001 were not removed from the impaired waters list even though the thresholds had changed. For the 2020 assessment process WDNR requested delisting of 91 waters with residual mercury listings from prior to 2001. This request was approved by US EPA.