Manitowoc County, Wisconsin
MA01
67400
72.61
Water is impaired due to one or more pollutants and associated quality impacts.
Notes
This water was originally listed in 1998 due to an impairment of the fish and aquatic life use caused by excess total phosphorus. A total phosphorus TMDL was approved by EPA in 2004.
Silver Lake was evaluated every two-year cycle from 2012 to 2024; phosphorus levels were confirmed to be elevated.Pollutant
Total Phosphorus
Listed For
Recreation
Impairments
Fish Kills, Excess Algal Growth, Eutrophication
Current Use
Restricted Recreation
Listing Status
TMDL Approved
Attainable Use
Recreation
Priority
Not Applicable
Designated Use
Recreation
303(d) ID
432
Listing Date
4/1/1998
Impaired Water Notes
This water was assessed during the 2018 listing cycle; new total phosphorus sample data exceeded 2018 WisCALM listing thresholds for the Recreation use and Fish and Aquatic Life use; chlorophyll data only exceeded REC thresholds, not FAL.
Date
7/11/2017
Impaired Water Notes
1. Reports are in the database. Monitoring has also been done during the summer 2009. All data are available, but have not been summarized in a report yet.
2. Personal reference per Paul Garrison (10/2009): Garrison’s best professional judgment is also to remove it from the list and no longer consider it impaired. Although macrophytes haven’t rebounded to the extent he would like, average TSI-chlorophyll for 2004-08 shows that it should no longer be considered impaired.
Date
10/22/2009
Impaired Water Notes
Silver Lake has received considerable best management practices including diverting Silver Creek from the lake, eradication and restocking with desirable fish species, and an alum treatment to seal the deep water sediments from phosphorus release. These management activities have improved the lake to a point where it can now be removed from the impaired waters list. Water quality monitoring has confirmed that the lake has improved since the completion of the restoration efforts. For instance, summer average secchi depth is 3.9 feet based on 32 samples collected between 7/15/2005 and 9/15/2009. Average chlorophyll TSI based on Carlson’s TSI calculations is 55 (‘Fair’ for Deep Seepage Lakes). This is below the natural community impairment threshold for TSI of 63 for deep seepage lakes. (Note: Using the Wisconsin chlorophyll TSI calculation, TSI-chl is 52, and average TSI-secchi is 58.) The average total phosphorus value is .035 mg/l based on May-Oct, 2004-2008 (or 0.034 mg/l based on 25 summer samples collected between 7/15/2005 and 9/15/2009). Although these TP data still exceed the impairment threshold of .02 mg/l for deep seepage lakes, Silver Lake showed improving TP levels from the 2004 alum treatment through 2007 (the 2008 values spiked due to extreme flooding). This lake has undergone extensive treatment and is greatly improved; as evidenced by the TSI-chl. values of 'Fair', it should no longer be considered impaired.
Date
10/18/2009
Impaired Water Notes
This water was assessed during the 2012 listing cycle, and total phosphorus and chlorophyll sample data exceed 2012 WisCALM listing thresholds for the recreation use.
Date
6/16/2011
Impaired Water Notes
The phosphorus TMDL for Silver Lake was approved by the USEPA March 23, 2004.
Date
3/23/2004
Impaired Water Notes
This water was assessed during the 2014 listing cycle; total phosphorus sample data overwhelmingly exceed 2014 WisCALM listing thresholds for the Recreation use, and chlorophyll data exceed REC thresholds. Total phosphorus and chlorophyll data do not exceed Fish and Aquatic Life thresholds.
Date
2/28/2014
Impaired Water Notes
This water was assessed during the 2016 listing cycle; total phosphorus and chlorophyll sample data exceeded 2016 WisCALM listing thresholds for the Recreation use, but did not exceed Fish and Aquatic Life thresholds.
Date
10/9/2015
Impaired Water Notes
This water was assessed during the 2020 listing cycle; new total phosphorus sample data exceeded 2020 WisCALM listing thresholds for the Recreation use and Fish and Aquatic Life use; chlorophyll data only exceeded REC thresholds, not FAL.
Date
6/19/2019
Impaired Water Notes
This water was assessed during the 2022 listing cycle; new total phosphorus sample data exceeded 2022 WisCALM listing thresholds for the Recreation use and Fish and Aquatic Life use; chlorophyll data only exceeded REC thresholds, not FAL.
Date
5/26/2021