Dane, Jefferson, Rock County, Wisconsin
LR04, LR11
808700
10,595.67
Water is impaired due to one or more pollutants and associated quality impacts.
Notes
Lake Koshkonong was added to the Impaired Waters List in 2002 for sediment, phosphorus, and low DO. The TMDL for these impairments was approved in 2011 (Rock River TMDL).
Evaluation of Lake Koshkonong in the 2020 and 2024 cycles confirmed the high phosphorus levels and identified excess algal blooms.Pollutant
Total Phosphorus
Listed For
Recreation
Impairments
Low DO, Excess Algal Growth, Eutrophication
Current Use
Restricted Recreation
Listing Status
TMDL Approved
Attainable Use
Recreation
Priority
Not Applicable
Designated Use
Recreation
303(d) ID
610
Listing Date
4/1/2002
Impaired Water Notes
TP and/or chlorophyll data from the period 2006-2010 were insufficient to assess per 2012 WisCALM. However, the previous assessment(s) were carried forward, and the lake remains listed as impaired.
Date
6/13/2011
Impaired Water Notes
Lake Koshkonong (808700) is a part of the Rock River Basin and is listed as impaired for total phosphorus and sediment/total suspended solids. The Rock River Basin TMDLs for phosphorus and sediment were approved by the USEPA September 28, 2011.
Date
5/8/2012
Impaired Water Notes
This water was assessed during the 2020 listing cycle; chlorophyll sample data exceeded 2020 WisCALM listing thresholds for the Recreation use and Fish and Aquatic Life use.
Date
8/7/2019
Impaired Water Notes
This water was assessed during the 2022 listing cycle; phosphorus and chlorophyll sample data exceeded 2022 WisCALM listing thresholds for the Recreation use and Fish and Aquatic Life use.
Date
4/20/2021
Pollutant
Sediment/Total Suspended Solids
Listed For
Fish and Aquatic Life
Impairments
Degraded Habitat, Turbidity
Current Use
Unsupported Aquatic Life
Listing Status
TMDL Approved
Attainable Use
WWSF - Warmwater Sport Fishery
Priority
Not Applicable
Designated Use
WWSF - Warmwater Sport Fishery
303(d) ID
610
Listing Date
4/1/2002
Impaired Water Notes
Lake Koshkonong (808700) is a part of the Rock River Basin and is listed as impaired for total phosphorus and sediment/total suspended solids. The Rock River Basin TMDLs for phosphorus and sediment were approved by the USEPA September 28, 2011.
Date
5/8/2012