Jefferson County, Wisconsin
UR02
830700
1,364.58
Condition has improved over time; water is not impaired.
Notes
Rock Lake was listed as impaired for mercury in fish tissue from 1998 to 2020. Rock Lake was evaluated every two-year cycle from 2014 to 2024; phosphorus and algae data indicated a healthy system. This lake is on the Waters Attaining Standards List. Pollutant
Mercury
Listed For
Impairments
NA
Current Use
Listing Status
Water Delisted
Attainable Use
Priority
Delisted 2020
Designated Use
303(d) ID
393
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