Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Lake Icaria IA 05-NOD-1398

Adams County S10T72NR34W 4 mi N of Corning.

Cycle
2022
Release Status
Final
Overall IR
4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trophic
Eutrophic
Trend
Stable
Created
12/30/2021 3:12:05 PM
Updated
1/26/2022 7:29:54 AM
Use Support
Class A1
Recreation - Primary contact
Not Supported
Support Level
Not Supported
Impairment Code
4a - Pollutant-caused impairment. TMDL has been completed.
Cause Magnitude
Slight
Status
Continuing
Source
Other: Sediment Resuspension
Source Confidence
Moderate
Cycle Added
2014
Impairment Rationale
Narrative criteria violation: aesthetically objectionable conditions
Data Source
Ambient monitoring: Iowa DNR-lakes
Class BLW
Aquatic Life - Lakes and wetlands
WINOFI
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
Moderate
Status
Continuing
Source
Other: Exotic Species
Source Confidence
Moderate
Cycle Added
2016
Impairment Rationale
Adverse impacts on plant/animal communities
Data Source
Biological monitoring: Iowa DNR Fisheries
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
Slight
Status
New
Source
Agriculture
Source Confidence
Low
Cycle Added
2022
Impairment Rationale
Adverse impacts on plant/animal communities
Data Source
Ambient monitoring: Iowa DNR-lakes
Class C
Drinking Water -
Fully Supported
Class HH
Human Health -
Fully Supported
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class A1 use was assessed (monitored) as “not supported” due to aesthetically objectionable conditions caused by poor water clarity. The Class BLW use was assessed (evaluated) as “WINOFI” due to poor water clarity and frequent cyanobacteria blooms. The Class C use was assessed (monitored) as “fully supported.” The Class HH (fish consumption) use was assessed (monitored) as "fully supported" based on fish tissue sampling data. Note: A TMDL for siltation at Lake Icaria was prepared by DNR and approved by EPA in 2003. Since all impairments for Lake Icaria were addressed in the TMDL, it will be listed as Category 4a for the current assessment/listing cycle.

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

WQ

CY 2016-2020

22020001

Lake Icaria

Iowa DNR

6

FT

See Below

59

Lake Icaria

Lake Icaria County Recreation Area

Class A1 - Indicator Bacteria: No Data

Class A1 - pH:

Site ID

Data Source ID

# Samples / # Years

Minimum Value

Maximum Value

Mean Value

# Violations

Violations needed for impairment

Violates Significantly >10% Rule?

Assessment Type

Support Level

22020001

6

14 / 5

7.3

8.6

8.2

0

4

NO

Monitored

Full

Class A1 - 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

22020001

6

Chlorophyll a TSI

15 / 5

31

73

49

NO

Monitored

Full

22020001

6

Secchi TSI

15 / 5

51

77

67

YES

Monitored

Not

22020001

6

Total Phosphorus TSI

15 / 5

49

76

64

NA

NA

NA

22020001

6

Inorganic suspended solids

15 / 5

0.6

16

3

NA

NA

NA

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

22020001

6

Ammonia

14 / 5

0.0003

0.328

0.08

NA

0 / 0

4

NO

Monitored

Full

22020001

6

Dissolved Oxygen

15 / 5

2.5

8.9

6.9

2

NA / NA

4

NO

Monitored

Full

22020001

6

pH

14 / 5

7.3

8.6

8.2

0

NA / NA

4

NO

Monitored

Full

22020001

6

Temperature

15 / 5

18.2

28.6

24.2

0

NA / NA

4

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

22020001

6

6

48.55

98.9%

18.57

57.9%

YES

Evaluated

3b

Class C - Conventional Parameters:

Site ID

Data Source ID

Parameter Name

# Samples / # Years

Minimum Value

Maximum Value

Mean Value

Median Value

# Violations

Violates Significantly >10% Rule?

Assessment Type

Support Level

22020001

6

Inorganic nitrogen (nitrate and nitrite)

15 / 5

0.02

1.6

0.4

0.035

0

NO

Monitored

Full

22020001

6

pH

14 / 5

7.3

8.6

8.2

8.2

0

NO

Monitored

Full

Class HH - Fish Tissue Sampling:

Site ID

Biopart

Year

Species

# in sample / # of samples

Avg Length (cm)

(Avg) Hg (ppm)

Chlordane (ppm)

Sum PCBs (ppm)

59

tissue plug

2020

channel catfish

20

53.1

0.123

59

tissue plug

2020

common carp

20

54.8

0.099

59

tissue plug

2019

largemouth bass

10

32.1

0.083

59

tissue plug

2020

walleye

5

49.2

0.153

59

tissue plug

2019

walleye

5

50.5

0.136

Support Level

Full

Monitoring and Methods
Assessment Key Dates
6/13/2016
Fixed Monitoring Start Date
9/23/2020
Fixed Monitoring End Date
1/30/2003
TMDL Completed
7/1/2019
Fish Tissue Monitoring
7/1/2020
Fish Tissue Monitoring
Methods
120
Surveys of fish and game biologists/other professionals
222
Non-fixed-station monitoring (conventional during key seasons and flows)
260
Fish tissue analysis
340
Primary producer surveys (phytoplankton/periphyton/macrophyton)