Briggs Woods Lake IA 04-UDM-1255
Hamilton County S17T88NR25W near Webster City.
- Cycle
- 2022
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trophic
- Eutrophic
- Trend
- Stable
- Created
- 12/30/2021 9:36:26 AM
- Updated
- 2/17/2022 11:06:01 AM
The Class A1 use was assessed (monitored) as "not supported" due to violations of the state's water quality criteria for pH and due to aesthetically objectionable conditions caused by algae blooms. The Class BLW use was assessed (monitored) as “not supported” (IR 5a) due to and violations of the state's water quality criteria for pH. The Class HH (fish consumption) use was assessed as “fully supported” based on fish tissue sampling data. Note: The DNR TMDL prepared for impairments due to algae and low dissolved oxygen (organic enrichment) was approved by U.S.EPA in July 2012. Thus, these impairments are moved from IR Category 5a (impaired; TMDL required) to Category 4a (impaired; TMDL approved). Because not all the impairments identified for this lake are covered by this TMDL (pH), this lake remains in IR Category 5a.
Data
Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description Iowa DNR 6 WQ CY 2016-2020 22400004 Briggs
Woods Lake Iowa DNR 6 FT See Below 77 Briggs
Woods Lake SE
of Webster City
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 22400004 6 15 / 5 8.3 9.3 8.7 1 4 NO Monitored Full According to DNR's methodology, a lake must meet water
quality standards for two consecutive cycles to suggest
de-listing. Therefore, Briggs Woods Lake will remain listed for the
2022 cycle as "not supported" its Class A1 use due to pH. 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 22400004 6 Chlorophyll a TSI 15 / 5 28 76 64 NO Monitored Full 22400004 6 Secchi TSI 15 / 5 48 80 67 YES Monitored Not 22400004 6 Total Phosphorus TSI 15 / 5 37 73 65 NA NA NA 22400004 6 Inorganic suspended solids 15 / 5 0.6 12.5 3.1 NA NA NA The level of inorganic suspended solids was relatively low and
does not suggest water quality problems due to non-algal turbidity. 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 22400004 6 Ammonia 15 / 5 0.0003 0.1279 0.02 NA 0 / 0 4 NO Monitored Full 22400004 6 Dissolved Oxygen 14 / 5 6.2 17.3 9.9 0 NA / NA 4 NO Monitored Full 22400004 6 pH 15 / 5 8.3 9.3 8.7 1 NA / NA 4 NO Monitored Full 22400004 6 Temperature 15 / 5 15.7 29.8 24.2 0 NA / NA 4 NO Monitored Full According to DNR's methodology, a lake must meet water
quality standards for two consecutive cycles to suggest
de-listing. Therefore, Briggs Woods Lake will remain listed for the
2022 cycle as "not supported" its Class BLW use due to pH. 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 22400004 6 6 20.94 100.0% 3.20 45.8% NO Evaluated NA 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) 77 tissue plug 2019 largemouth bass 11 35.3 0.093
77 tissue plug 2017 largemouth bass 3 40.4 0.247
Support Level Full