Garlock Slough IA 06-LSR-1654
Dickinson County S35T99NR37W 2.5 mi. NW of Milford.
- Cycle
- 2022
- Release Status
- Final
- Overall IR
- 3 - Insufficient data exist to determine whether any designated uses are met.
- Trend
- Stable
- Created
- 1/4/2022 10:44:07 AM
- Updated
- 2/17/2022 2:51:36 PM
The Class BLW use was assessed (evaluated) as "WINOFI" due to violations in the class BLW criteria 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 2017-2018 14000183 Garlock
Slough
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 14000183 6 Chlorophyll a TSI 10 / 2 24 83 52 NO Evaluated Full 14000183 6 Total Phosphorus TSI 10 / 2 61 105 72 NA NA NA 14000183 6 Inorganic suspended solids 10 / 2 0.06 17 9 NA NA NA The TSI value for Secchi depth is not used to evaluate the
attainment of 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 uses, 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
uses are 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 14000183 6 Dissolved Oxygen 7 / 2 1.26 5.24 3.65 5 NA / NA 3 YES Evaluated WINOFI 14000183 6 pH 7 / 2 7.39 8.74 7.8 0 NA / NA 3 NO Evaluated Full 14000183 6 Temperature 7 / 2 17.92 25.89 22.15 0 NA / NA 3 NO Evaluated Full 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 14000183 6 Total suspended solids 10 / 2 0.5 83 10.8 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 in wetlands and shallow lakes. High levels of
total suspended solids impede the growth of submersed aquatic vegetation (SAV).
Submersed aquatic vegetation 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. Class
HH - No Data