Dan Greene Slough IA 06-LSR-1634
Clay County S20T97NR35W 5 mi N of Dickens.
- Cycle
- 2022
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Stable
- Created
- 1/4/2022 9:12:22 AM
- Updated
- 2/17/2022 2:50:36 PM
The Class BLW use was assessed as "not supported" due to violations of the class BLW criteria for dissolved oxygen and pH. 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 2016-2018 22100004 Dan
Greene 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 22100004 6 Chlorophyll a TSI 10 / 2 24 81 56 NO Evaluated Full 22100004 6 Total Phosphorus TSI 10 / 2 51 79 60 NA NA NA 22100004 6 Inorganic suspended solids 10 / 2 0 44 2 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 22100004 6 Ammonia 5 / 1 0.025 0.051 0.03 NA 0 / 0 2 NO Evaluated Full 22100004 6 Dissolved Oxygen 10 / 2 1.8 9.2 6.6 3 NA / NA 3 YES Monitored Not 22100004 6 pH 10 / 2 7.4 10.5 8.4 3 NA / NA 3 YES Monitored Not 22100004 6 Temperature 10 / 2 15 29 22 0 NA / NA 3 NO Monitored 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 22100004 6 Total suspended solids 10 / 2 0.6 48 6.2 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 - Toxic Parameters: No Data Additional Notes:
Monitoring of fish and aquatic vegetation populations at Dan
Greene Slough by DNR staff also suggests that the water quality has improved in
this wetland. These results further indicate that the aquatic life uses of this
wetland should be assessed as "fully supported."Dan Greene Slough was
drawn down and rough fish removed between 2008 and 2010.