Crystal Lake IA 02-IOW-781
Hancock County S15T97NR25W at Crystal Lake.
- 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 9:54:56 AM
- Updated
- 2/17/2022 9:28:10 AM
The Class A1 use was assessed (monitored) as “not supported” due to aesthetically objectionable conditions caused by poor water transparency and nuisance blooms of algae. The Class BLW use was assessed (evaluated) as “WINOFI” due to a fish kill due to natural causes and high cyanobacteria concentrations. The Class HH (fish consumption) use was assessed as "fully supported" based on fish tissue sampling data. Note: A TMDL for organic enrichment at Crystal Lake was prepared by DNR and approved by EPA in 2002; thus, this waterbody was placed into IR Category 4a (TMDL approved). Because all of the Section 303(d) impairments identified for this assessment/listing cycle, it remains listed as Category 4a (TMDL approved) for this assessment/listing cycle.
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site Name Site Description Iowa DNR 6 WQ CY 2016-2020 22410001 Crystal Lake Max
Depth Iowa DNR 6 FT See Below 292 Crystal Lake Crystal Lake Roadside
Park / Crystal Hills WMA
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 22410001 6 15 / 5 8.3 9.1 8.7 1 4 NO Monitored Full Crystal Lake was assessed as "not supported" for the
2008 assessment/listing cycle due to frequent violations of the state Class A1
criterion for pH. Based on DNR’s assessment methodology 2 consecutive
assessment/listing cycles without significantly greater than 10% of the samples
violating the single-sample maximum criterion are necessary to propose
delisting based on pH violations. There were less than 10% of the samples
exceeding the single-sample maximum criterion for the 2020 and the current
2022 assessment listing cycle. Therefore, the impairment for pH is
suggested for delisting for the 2022 assessment/listing cycle. 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 22410001 6 Chlorophyll a TSI 15 / 5 36 82 65 YES Monitored Not 22410001 6 Secchi TSI 15 / 5 51 77 73 YES Monitored Not 22410001 6 Total Phosphorus TSI 15 / 5 51 86 76 NA NA NA 22410001 6 Inorganic suspended solids 15 / 5 0.4 46 4 NA NA NA 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 22410001 6 Ammonia 15 / 5 0.0003 0.167 0.04 NA 0 / 0 4 NO Monitored Full 22410001 6 Dissolved Oxygen 14 / 5 4.4 12.3 8.5 1 NA / NA 4 NO Monitored Full 22410001 6 pH 15 / 5 8.3 9.1 8.7 1 NA / NA 4 NO Monitored Full 22410001 6 Temperature 15 / 5 14.2 29.1 23.1 0 NA / NA 4 NO Monitored Full Crystal Lake was assessed as "not supported" for the
2008 assessment/listing cycle due to frequent violations of the state Class A1
criterion for pH. Based on DNR’s assessment methodology 2 consecutive
assessment/listing cycles without significantly greater than 10% of the samples
violating the single-sample maximum criterion are necessary to propose
delisting based on pH violations. There were less than 10% of the samples
exceeding the single-sample maximum criterion for the 2020 and the current
2022 assessment listing cycle. Therefore, the impairment for pH is
suggested for delisting for the 2022 assessment/listing cycle. 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 22410001 6 5 273.58 99.2% 81.58 96.1% YES Evaluated 3b Class BLW - Fish Kill: The Class BLW use was assessed (evaluated) as “WINOFI” based on results of a fish kill investigation in October of 2015. Because the cause of the fish kill was not
identified, or the fish kill was attributed to a non-pollutant cause (e.g.,
winterkill), the assessment type is “evaluated.” Segments assessed using
“evaluated” assessments are placed in Category 3b and are added to the state
list of waters in need of further investigation. If no additional fish kills
are reported in the segment for a 10 year period, the Category will be changed
from 3b to 3a (water not assessed). Details about the 2015 fish kill can be found
here:https://programs.iowadnr.gov/fishkill/Events/888,https://programs.iowadnr.gov/fishkill/Events/821
Class HH - Fish
Tissue Sampling: Site ID Biopart Year Species # in sample / # of samples Avg Length (cm) (Avg) Hg (ppm) Chlordane (ppm) Sum PCBs (ppm) 292 tissue plug 2020 northern pike 2 66.4 0.156
292 tissue plug 2019 northern pike 8 61.9 0.165
292 tissue plug 2020 walleye 1 51.1 0.223
292 tissue plug 2019 walleye 1 44.2 0.192
Support Level Full