Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Cedar River IA 02-CED-462

from bridge crossing in LaPorte City in S19 T87N R11W Black Hawk Co.) to dam of Cedar Falls Impoundment in NW 1/4 S12 T89N R14W Black Hawk Co.

Cycle
2024
Release Status
Final
Overall IR
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
11/1/2023 8:12:40 AM
Updated
1/12/2024 2:18:28 PM
Use Support
Class A1
Recreation - Primary contact
Not Supported
Support Level
Not Supported
Impairment Code
5a - Pollutant-caused impairment. TMDL needed.
Cause Magnitude
Slight
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2008
Impairment Rationale
Geometric mean criterion exceeded
Data Source
Ambient monitoring: Iowa DNR-rivers
TMDL Priority
Tier III
Class BWW1
Aquatic Life - Warm Water Type 1
WINOFI
Impairment Code
3b-u - Use potentially biologically impaired based on uncalibrated IBI metrics.
Cause Magnitude
Moderate
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2008
Impairment Rationale
Potential Impairment
Data Source
Biological monitoring: Iowa DNR WQMA
Class HH
Human Health -
WINOFI
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
Slight
Status
New
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2024
Impairment Rationale
Potential Impairment
Data Source
Fish contaminant monitoring: Iowa DNR
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class A1 use was assessed as "not supported" due to levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW1 use was assessed as "WINOFI" based on biological sampling data. The Class HH (fish consumption) use was assessed as "WINOFI" based on an average walleye sample above the mercury consumption advisory threshold.

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

WQ

CY 2012-2014

10070006

Cedar River downstream of Waterloo

Iowa DNR

6

BIO

See Below

848

Cedar River

Downstream of Waterloo

Iowa DNR

6

BIO

See Below

1100

Cedar River

Above LaPorte City

Iowa DNR

6

BIO

See Below

1102

Cedar River

George Wyth State Park

Iowa DNR

6

FT

See Below

1218

Cedar River

Waterloo

Iowa DNR

6

FT

See Below

1369

Cedar River (U)

Waterloo


Class A1 – Indicator Bacteria: 2012-2014

Site ID

Data Source ID

# Samples / # Years

2012 Geometric Mean

2013 Geometric Mean

2014 Geometric Mean

Annual Geometric Mean Violation

# Violations

% Violations

Significantly >10% Violations

Assessment Type

Support Level

10070006

6

22 / 3

97

165

172

Yes

6

27%

Yes

Evaluated

Not


Class A1 - pH: 2012-2014

Site ID

Data Source ID

# Samples / # Years

Maximum Value

Mean Value

Median Value

# Violations

% Violations

Significantly >10% Violations

Assessment Type

Support Level

10070006

6

33 / 3

9

8.24

8.3

0

0%

No

Evaluated

Full


Class BWW1 - Binomial Parameters: 2012-2014

Site ID

Data Source ID

Parameter Name

# Samples / # Years

Maximum Value

Mean Value

Median Value

# Acute / Chronic Violations

% Acute/ Chronic Violations

Significantly >10% Violations

Assessment Type

Support Level

10070006

6

Ammonia

33 / 3

1.7

0.19

0.05

0 / 0

0% / 0%

No

Evaluated

Full

10070006

6

Chloride

33 / 3

72

30.4

28

0 / 0

0% / 0%

No

Evaluated

Full

10070006

6

Dissolved oxygen

33 / 3

17.3

11.5

11.7

NA / 0

NA / 0%

No

Evaluated

Full

10070006

6

pH

33 / 3

9

8.24

8.3

0 / NA

0% / NA

No

Evaluated

Full

10070006

6

Sulfate

33 / 3

47

33.4

34

0 / NA

0% / NA

No

Evaluated

Full

10070006

6

Temperature

33 / 3

27

11.7

12.4

0 / 0

0% / 0%

No

Evaluated

Full


Class BWW1 - Biological Sampling:


Benthic Macroinvertebrates:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

BM Sample Gear

BMIBI score

BMIBI Class

47c BMIBI BIT

BMIBI Pass/Fail

848

9/9/14

5234

47c

MS

Hess

56

Good

70

Fail

848

9/9/14

5234

47c

MS

Floating Art Sub

51

Fair

52

Fail


Fish:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

Riffle Stream?

FIBI score

FIBI Class

47c FIBI BIT

FIBI Pass/Fail

1100

9/22/20

5505

47c

MS

Undetermined

4

Poor

44

Fail

1102

9/7/17

5790

47c

MS

Undetermined

4

Poor

44

Fail


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (0/2)

WINOFI

Fish

Evaluated

Fail (0/2)

WINOFI

3bu

Assessment was evaluated because the drainage area of

Overall

Evaluated

Fail

WINOFI

the sample site was greater than the calibrated range.


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)

1218

tissue plug

2021

channel catfish

5

54.0

0.165

1218

tissue plug

2021

common carp

10

53.8

0.109

1218

tissue plug

2021

walleye

6

45.5

0.366

1369

tissue plug

2019

walleye

7

46.1

0.261

1369

tissue plug

2020

channel catfish

10

53.8

0.192

1369

tissue plug

2021

walleye

2

44.8

0.194

1369

tissue plug

2021

smallmouth bass

20

31.5

0.218

1369

tissue plug

Support Level

WINOFI

Monitoring and Methods
Assessment Key Dates
1/5/2012
Monitoring Start
9/9/2014
Monitoring End
9/9/2014
Biological Monitoring
9/22/2020
Biological Monitoring
9/7/2017
Biological Monitoring
7/1/2019
Fish Tissue Monitoring
7/1/2020
Fish Tissue Monitoring
7/1/2021
Fish Tissue Monitoring
Methods
150
Monitoring data more than 5 years old
200
Physical/Chemical Monitoring
260
Fish tissue analysis
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys
420
Indicator bacteria monitoring