Mariposa Lake IA 03-NSK-867
Jasper County S32T81NR18W 6 mi. NE of Newton.
- Cycle
- 2022
- Release Status
- Final
- Overall IR
- 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
- Trophic
- Hypereutrophic
- Trend
- Stable
- Created
- 12/22/2021 2:27:46 PM
- Updated
- 2/17/2022 10:12:35 AM
The Class A1 use was assessed (monitored) as “not supported” due to aesthetically objectionable conditions caused by poor water transparency and nuisance algae blooms. The Class BLW use was assessed as “fully supported.” Sedimentation also remains a concern at this lake. All other designated uses were “not assessed.” Note: A TMDL for algae and turbidity at Mariposa Lake was prepared by DNR and approved by EPA in 2004; thus, this waterbody was placed into IR Category 4a (TMDL approved) for the 2004 assessment/listing cycle. Because all Section 303(d) impairments identified for the current assessment/listing cycle (algal growth and turbidity) are addressed by the TMDL, this waterbody remains in IR Category 4a.
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description Iowa DNR 6 WQ CY 2016-2020 22500002 Mariposa
Lake
Class A1 - Indicator Bacteria: No Data Class A1 - pH: Site ID Data Source ID # Samples / # Years Minimum Value Maximum Value Mean Value # Violations Violations needed for impairment Violates Significantly >10% Rule? Assessment Type Support Level 22500002 6 8 / 3 8.1 9.2 8.6 2 3 NO Evaluated Full Class A1 - Lake TSI's: Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Median Value Median TSI Violation? Assessment Type Support Level 22500002 6 Chlorophyll a TSI 8 / 3 36 70 55 NO Evaluated Full 22500002 6 Secchi TSI 8 / 3 47 73 62 NO Evaluated Full 22500002 6 Total Phosphorus TSI 8 / 3 46 85 74 NA NA NA 22500002 6 Inorganic suspended solids 8 / 3 0.3 8 4.4 NA NA NA Although the index value for Chlorophyll a was below the
impairment trigger of 65 for this assessment cycle, the Class A1 use of Mariposa Lake remains "not supported" due to aesthetically objectionable
conditions. Based on DNR's methodology, the median TSI value for Chlorophyll a
must be 63 or less for two consecutive assessment/listing cycles before a lake can be removed from the state's Section 303(d) list (IR Category 5). Therefore,
Mariposa Lake will remain listed as "not supported" for the 2022
assessment/listing cycle. Although the index value for Secchi is below the impairment
trigger of 65 for this assessment cycle, the Class A1 use of Mariposa Lake remains "not supported" due to aesthetically objectionable conditions.
Based on DNR's methodology, the median TSI value for Secchi must be 63 or less
for two consecutive assessment/listing cycles before a lake can be removed
from the state's Section 303(d) list (IR Category 5). Therefore, Mariposa
Lake will remain listed as "not supported" for the 2022
assessment/listing cycle. Class BLW - Conventional Parameters: Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Mean Value # Violations # Acute / Chronic Violations Violations needed for impairment Violates Significantly >10% Rule? Assessment Type Support Level 22500002 6 Ammonia 8 / 3 0.004 0.182 0.06 NA 0 / 0 3 NO Evaluated Full 22500002 6 Dissolved Oxygen 8 / 3 6.6 13.5 9.6 0 NA / NA 3 NO Evaluated Full 22500002 6 pH 8 / 3 8.1 9.2 8.6 2 NA / NA 3 NO Evaluated Full 22500002 6 Temperature 8 / 3 19.1 28.7 24 0 NA / NA 3 NO Evaluated Full Class BLW - Lake Planktonic Cyanobacteria: Site ID Data Source ID # Samples Maximum Cyanobacteria Wet Mass Maximum Cyanobacteria % Composition Median Cyanobacteria Wet Mass Median Cyanobacteria % Composition Median Cyanobacteria Concentration = 75th Percentile Assessment Type Support Level 22500002 6 4 11.70 98.4% 3.95 16.2% NO Evaluated NA
Class HH: No Data