Assessment Summary
The Class BLW use was assessed as "not supported" due to high levels of algae and suspended solids at this shallow lake that suggest impairment due to adverse impacts on plant/animal communities. Additionally, the Class BLW use was assessed as "not supported" due to violations of the Class BLW criterion for pH. All other designated uses were “not assessed.”
Assessment Explanation
Data Sources:
|
Data Source
|
Data Source ID
|
Data Type
|
Data Age
|
Site ID
|
Site
Name
|
Site
Description
|
|
Iowa DNR
|
6
|
WQ
|
CY 2022-2024
|
14000290
|
Iowa
Lake
|
|
Class BLW - 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
|
|
14000290
|
6
|
Chlorophyll a TSI
|
14 / 3
|
72
|
89
|
79
|
YES
|
MONITORED
|
NOT
|
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 was used to determine whether or not the Class BLW use was
impaired in these shallow systems.
Class BLW - Binomial 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
|
|
14000290
|
6
|
Dissolved Oxygen
|
14 / 3
|
4.86
|
20.33
|
11.49
|
1
|
NA / NA
|
4
|
NO
|
MONITORED
|
FULL
|
|
14000290
|
6
|
pH
|
14 / 3
|
5.82
|
9.68
|
8.58
|
4
|
NA / NA
|
4
|
YES
|
MONITORED
|
NOT
|
|
14000290
|
6
|
Temperature
|
14 / 3
|
19.002
|
28.853
|
23.552
|
0
|
NA / NA
|
4
|
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
|
|
14000290
|
6
|
Total suspended solids
|
14 / 3
|
21
|
140
|
82
|
YES
|
MONITORED
|
NOT
|
Guidelines for wetland assessment from the Upper Mississippi River
Conservation Committee’s Water Quality Technical Section (2003) state that a
median 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.
Class BLW - Toxic Parameters:
|
Site ID
|
Data Source ID
|
Parameter Name
|
# Samples / # Years
|
Maximum Value
|
Mean Value
|
Median Value
|
# Acute / Chronic Violations
|
>1 Acute / Chronic Violation
|
Assessment Type
|
Support Level
|
|
14000290
|
6
|
Ammonia
|
9 / 2
|
0.47
|
0.13
|
0.02
|
0 / 0
|
NO
|
EVALUATED
|
FULL
|
According to local DNR
fisheries Biologist, this lake has excessive turbidity and little to no aquatic
plant life. Turbidity issues likely due to excessive nutrients and/or high
densities of common carp. Additionally, according to Water Quality Bureau
Monitoring Staff, this system suffers from high turbidity and significant algal
blooms. This information corroborated the existing impairment on this system.
Class
HH - Fish Tissue sampling: No Data
In general, Iowa wetlands
are not managed for recreational fisheries; thus, fish contaminant monitoring
is not typically conducted at these waterbodies.
