Lake Hendricks IA 01-WPS-356
Howard County S19T99NR14W 0.5 mi NE of Riceville.
- Cycle
- 2024
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trophic
- Hypereutrophic
- Trend
- Improving
- Trend Comment
- pH violation have lowered leading to the delisting of the pH impairment of this waterbody in 2024
- Created
- 11/1/2023 8:12:41 AM
- Updated
- 2/2/2024 2:47:44 PM
| Cycle Added | Class | Cause | Data Source | Rationale |
|---|---|---|---|---|
| 2006 | Class A1 | pH | Ambient monitoring: Iowa DNR-lakes | New data: WQ improvement (chemical / physical / bacterial) |
| 2006 | Class BLW | pH | Ambient monitoring: Iowa DNR-lakes | New data: WQ improvement (chemical / physical / bacterial) |
The Class A1 use was assessed as “not supported” due to aesthetically objectionable conditions caused by algae blooms. The level of inorganic suspended solids was relatively low and does not suggest water quality problems due to non-algal turbidity. The Class BLW use was assessed as “fully supported” based on water quality monitoring data. The Class HH (fish consumption) use was assessed as "fully supported" based on fish tissue sampling data.
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description Iowa DNR 6 WQ CY 2018-2022 22450001 Lake
Hendricks Lake
Deep Point Iowa DNR 6 FT See below 1079 Lake
Hendricks
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 22450001 6 12 / 4 7.9 9.2 8.5 1 4 NO Mon Full ·
Lake Hendricks was assessed as "not
supported" for the 2006 assessment/listing cycle due to frequent
violations of the state Class A1 criterion for pH. Based on DNR’s assessment
methodology the current assessment/listing cycles must have fewer violations of
the criterion based on the minimum required by on the 10% Rule to propose
delisting pH. There were less than 10% of the samples exceeding the
single-sample maximum criterion for the 2024 assessment/listing cycle.
Therefore, the impairment for pH is suggested for delisting for the 2024
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 22450001 6 Chlorophyll a TSI 12 / 4 46 77 70 YES Mon Not 22450001 6 Secchi TSI 12 / 4 49 83 70 YES Mon Not 22450001 6 Total Phosphorus TSI 12 / 4 37 78 72 NA NA NA 22450001 6 Fixed suspended solids 12 / 4 0.6 17 4 NA NA NA Class BLW - Binomial 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 22450001 6 Dissolved Oxygen 12 / 4 5.6 13.5 8.3 0 NA / NA 4 NO Mon Full 22450001 6 pH 12 / 4 7.9 9.2 8.5 1 NA / NA 4 NO Mon Full 22450001 6 Temperature 12 / 4 16.8 26.9 22.8 0 NA / NA 4 NO Mon Full ·
Lake Hendricks was assessed as "not
supported" for the 2006 assessment/listing cycle due to frequent
violations of the state Class A1 criterion for pH. Based on DNR’s assessment
methodology the current assessment/listing cycles must have fewer violations of
the criterion based on the minimum required by on the 10% Rule to propose
delisting pH. There were less than 10% of the samples exceeding the
single-sample maximum criterion for the 2024 assessment/listing cycle.
Therefore, the impairment for pH is suggested for delisting for the 2024
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 22450001 6 4 32.39797121 93% 3.520509207 33% NO Evaluated NA Class BLW - Toxic Parameters: Site ID Data Source ID Parameter Name # Samples / # Years Maximum Value Mean Value Median Value # Acute / Chronic Violations >1 Acute / Chronic Violation Assessment Type Support Level 22450001 6 Ammonia 12 / 4 0.279 0.12 0.12 0 / 0 NO Mon Full 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) 1079 tissue plug 2019 largemouth bass 10 33.2 0.168
Support Level Full