Lizard Lake IA 04-UDM-1281
Pocahontas County S22T91NR34W 4 mi SW of Gilmore City.
- Cycle
- 2022
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Improving
- Trend Comment
- Suspended solids and Chloryphll a have be reduced in this system due to restoration practices.
- Created
- 12/30/2021 9:49:48 AM
- Updated
- 4/5/2022 8:27:26 AM
The Class BLW use was assessed (monitored) as "not supported" due to violations of the Class BLW criterion for dissolved oxygen. All other designated uses were “not assessed.”
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description Iowa DNR 6 WQ CY 2016-2019 22760001 Lizard
Lake
Class BLW - TSI's Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Median Value Median TSI Violation? Assessment Type Support Level 22760001 6 Chlorophyll a TSI 23 / 4 24 70 48 NO Monitored Full 22760001 6 Total Phosphorus TSI 23 / 4 53 80 71 NA NA NA 22760001 6 Inorganic suspended solids 18 / 3 0 10 1 NA NA NA The TSI value for Secchi depth is not used to evaluate the
attainment of the aquatic life use in shallow lakes. Due to the depth of these shallow
lakes, TSI values for Secchi depth can be misleading. In some instances, the
Secchi disk remains visible at the bottom of the lake and the depth of the lake
is recorded as the Secchi depth. In these instances, water clarity may be
sufficient to support the Class BLW use, but the index value is limited by
the depth of the lake. Thus the combination of total suspended solids and
chlorophyll a will be used to determine whether or not the Class BLW use is impaired in these shallow systems. 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 22760001 6 Ammonia 18 / 3 0.0003 0.42 0.08 NA 0 / 0 4 NO Monitored Full 22760001 6 Dissolved Oxygen 23 / 4 0.3 11 5.9 10 NA / NA 5 YES Monitored Not 22760001 6 pH 23 / 4 7.01 9.72 7.77 1 NA / NA 5 NO Monitored Full 22760001 6 Temperature 23 / 4 15 29.08 22.51 0 NA / NA 5 NO Monitored 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 22760001 6 3 0.06 3.8% 0.05 0.8% NO Evaluated NA Class BLW - Protection of Submerged Aquatic Vegetation: Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Median Value Median Value = SAV Assessment Type Support Level 22760001 6 Total suspended solids 23 / 4 0.5 16.7 5 NO Monitored Full Guidelines for wetland assessment from the Upper Mississippi River Conservation Committee’s Water Quality Technical Section (2003) state that an average total suspended solids concentration during the growing season of less than 30 mg/L is necessary to provide sufficient water clarity to support the growth of submersed aquatic vegetation (SAV) in wetlands and shallow lakes. High levels of total suspended solids impede the growth of SAV. SAV is critical to the health of wetland and shallow lake ecosystems. The elimination of SAV can degrade habitat quality such that undesirable aquatic species such as cyanobacteria, common carp and fathead minnows dominate. As such, the suppression of SAV constitutes a violation of Iowa’s narrative water quality criteria protecting against undesirable or nuisance aquatic life.