Impaired Water - Oconomowoc Lake (Oconomowoc Lake)
Waukesha County, Wisconsin
UR09
849600
795.30
Proposed for removal from impaired waters during assessment period.
Notes
Oconomowoc 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.
Listing Details
Pollutant
Mercury
Listed For
Impairments
NA
Current Use
Listing Status
Delist
Attainable Use
Priority
Not Applicable
Designated Use
303(d) ID
326
Listing Date
4/1/1998
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.
Date
9/4/2018