Marble Lake IA 06-LSR-1656
Dickinson County S17T100NR36W 3.5 mi. NE of Montgomery.
- Cycle
- 2022
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Stable
- Created
- 1/4/2022 10:58:50 AM
- Updated
- 2/17/2022 2:51:59 PM
| Cycle Added | Class | Cause | Data Source | Rationale |
|---|---|---|---|---|
| 2014 | Class BLW | Algal Growth: Chlorophyll a | Ambient monitoring: Iowa DNR-shallow lakes & wetlands | New data: WQ improvement (chemical / physical / bacterial) |
The Class BLW use was assessed (monitored) as "not supported" due to violations of the class BLW criteria for 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 2016-2020 22300017 Marble
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 22300017 6 Chlorophyll a TSI 20 / 4 24 75 63 NO Monitored Full 22300017 6 Total Phosphorus TSI 20 / 4 57 78 68 NA NA NA 22300017 6 Inorganic suspended solids 10 / 2 1.08 36 7.15 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. DNR's assessment methodology indicates that at least two
assessment/listing cycles with a TSI value less than or equal to 63 are
necessary to suggest de-listing of an impairment. The chlorophyll a
TSI value for the 2014 assessment listing cycle was 68, which based on DNR's
assessment/listing methodology indicated an impairment based on the narrative
criteria protecting against aesthetically objectionable conditions. Because the
TSI value for the 2020 assessment/listing cycle was less than the trigger of 65
(2020 listing for chlorophyll a was 62), and because the TSI value for the
current listing cycle is also 63, based on DNR's methodology, these values
suggest "full support" of the Class A1 uses protecting against
aesthetically objectionable conditions and the impairment (5a) for chlorophyll
a is suggested for delisting for the 2022 assessment/listing cycle. 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 22300017 6 Ammonia 14 / 3 0.025 0.316 0.07 NA 0 / 1 4 NO Monitored Full 22300017 6 Dissolved Oxygen 20 / 4 5.78 19.16 10.17 0 NA / NA 5 NO Monitored Full 22300017 6 pH 20 / 4 7.64 11.13 8.95 7 NA / NA 5 YES Monitored Not 22300017 6 Temperature 20 / 4 14 28.2 22.4 0 NA / NA 5 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 22300017 6 Total suspended solids 20 / 4 7 50 15 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