Polk County, Wisconsin
SC06
2628600
147.08
Water is impaired due to one or more pollutants and associated quality impacts.
Notes
White Ash Lake was evaluated for phosphorus and algae every two years between 2012 and 2024. Phosphorus levels were found to be too high, which was reflected in algal blooms. This lake is covered by a restoration plan: Implementation Plan for the Lake St. Croix Nutrient Total Maximum Daily Load (expires 2025).Pollutant
Total Phosphorus
Listed For
Recreation
Impairments
Excess Algal Growth, Eutrophication
Current Use
Restricted Recreation
Listing Status
303d Listed
Attainable Use
Recreation
Priority
Low
Designated Use
Recreation
303(d) ID
2012-1
Listing Date
4/1/2012
Impaired Water Notes
This water was assessed during the 2018 listing cycle; new total phosphorus and chlorophyll sample data exceeded 2018 WisCALM listing thresholds for the Recreation use and Fish and Aquatic Life use.
Date
7/10/2017
Impaired Water Notes
Not recommended for 2010 listing but we have added this based on 2012 TP and Chl A package and the TP standard. This lake is likely to be naturally eutrophic but a study should be conducted to determine if indeed natural background levels are the cause of the conditions. White Ash Lake is high in both Total Phosphorus and TSI-chlorophyll.
The Average Total Phosphorus is .12 mg/l (2007-2008), which exceeds the threshold of .04 mg/l for shallow lowland lakes. Using the Carlson TSI calculation for 2004-2008, average TSI-chlorophyll is 73, which also exceeds the threshold of 71 for shallow lowland lakes. However, there are several sources of documentation that Polk County has both higher than normal groundwater phosphorus concentrations and high soils/geologic phosphorus concentrations, with high-nutrient glacial outwash till. These contribute to naturally eutrophic conditions in many of the lakes in the area. Previous White Ash Lake monitoring, modeling, and management planning efforts are limited, outdated, and tend to focus only on aquatic plants. As resources allow, we recommend additional monitoring & investigation into whether there are any anthropogenic sources that may be contributing to phosphorus levels (e.g., sediment core, etc.). Additionally, this lake currently has high macrophyte growth rather than being algae dominated.
The lake needs to be managed properly to maintain the macrophyte-driven system and prevent it from converting to an algae-driven system. Since extensive harvesting programs have been initiated on North White Ash, monitoring to determine whether Secchi & chlorophyll concentrations have changed post-harvesting would also be beneficial.
Date
6/7/2011
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 exceeded Fish and Aquatic Life use, however, chlorophyll data only exceeds REC thresholds.
Date
2/28/2014
Impaired Water Notes
This water was assessed during the 2016 listing cycle; total phosphorus sample data overwhelmingly exceed 2016 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
10/12/2015
Impaired Water Notes
This water was assessed during the 2020 listing cycle; total phosphorus and chlorophyll sample data exceeded 2020 WisCALM listing thresholds for the Recreation use and Fish and Aquatic Life use. This lake is covered by the following restoration plan and was classified as Category 5W as a result: Implementation Plan for the Lake St. Croix Nutrient Total Maximum Daily Load (2025).
Date
7/24/2019
Impaired Water Notes
This water was assessed during the 2022 listing cycle; total phosphorus and chlorophyll sample data exceeded 2022 WisCALM listing thresholds for the Recreation use and Fish and Aquatic Life use.
Date
5/26/2021