Iowa DNR
ADBNet

Water Quality Assessments

Impaired Waters List

Cedar River IA 02-CED-477

from upper end of Nashua Impoundment (Chickasaw/Floyd county line (W line S7 T94N R14W Chickasaw Co.)) to Dam No. 2 at Charles City in NW 1/4 NE 1/4 S12 T95N R16W Floyd Co.

Assessment Cycle
2020
Release Status
Final
Data Collection Period
Overall IR Category
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
8/28/2020 1:47:23 PM
Updated
10/26/2020 10:17:58 AM
Assessment conducted in accordance with Iowa's 2020 IR methodology
Use Support
Class A1
Partially Supported
Bacteria: Indicator Bacteria- E. coli
Support Level
Partially 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
WINOFI
Biological: low aquatic macroinvertebrate IBI
Support Level
Water in Need of Further Investigation (WINOFI)
Impairment Code
3b-u - Use potentially biologically impaired based on uncalibrated IBI metrics.
Cause Magnitude
Slight
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2004
Impairment Rationale
Low Biotic Index
Data Source
Biological monitoring: Iowa DNR WQMA
Class HH
Partially Supported
Fish Consumption Advisory: Mercury
Support Level
Partially Supported
Impairment Code
5a - Pollutant-caused impairment. TMDL needed.
Cause Magnitude
Slight
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2014
Impairment Rationale
Potential fish consumption advisory; additional sampling needed
Data Source
Fish contaminant monitoring: Iowa DNR
TMDL Priority
Tier IV
General Use
Not Assessed
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class A1 use was assessed as "partially supported" due to violations of Class A1 criteria for indicator bacteria (E. coli). The Class BWW1 use was assessed as "partially supported" based on biological sampling data. The Class HH use remains assessed as "partially supported" based on fish tissue sampling data.

Assessment Explanation

Sources of Data:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

WQ

CY 2016-2018

10340001

Cedar River near Charles City (DS1)

Iowa DNR

6

BIO

See Below

285

Cedar River

Carrville/Charles City

Iowa DNR

6

FT

See Below

61

Cedar River

At Midway


Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples / # Years

2016 Geometric Mean

2017 Geometric Mean

2018 Geometric Mean

Annual Geometric Mean Violation

# Violations

% Violations

Significantly >10% Violations

Assessment Type

Support Level

10340001

6

20 / 3

165.63

57.47

153.09

Yes

7

35%

Yes

Monitored

Partial


Class A1 - pH:

Site ID

Data Source ID

# Samples / # Years

Maximum Value

Mean Value

Median Value

# Violations

% Violations

Significantly >10% Violations

Assessment Type

Support Level

10340001

6

36 / 3

8.7

8.2

8.3

0

0%

No

Monitored

Full


Class BWW1 - Conventional Parameters:

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

10340001

6

Ammonia

36 / 3

1.9

0.12

0.02

0 / 0

0% / 0%

No

Monitored

Full

10340001

6

Chloride

36 / 3

36

23

24

0 / 0

0% / 0%

No

Monitored

Full

10340001

6

Dissolved oxygen

36 / 3

15.2

11.2

11.4

NA / 0

NA / 0%

No

Monitored

Full

10340001

6

pH

36 / 3

8.7

8.2

8.3

0 / NA

0% / NA

No

Monitored

Full

10340001

6

Sulfate

36 / 3

32

22.3

21

0 / NA

0% / NA

No

Monitored

Full

10340001

6

Temperature

36 / 3

25.6

11.2

10.2

0 / 0

0% / 0%

No

Monitored

Full


Class BWW1 - Toxic Parameters:

Site ID

Data Source ID

Parameter Name

# Samples / # Years

Maximum Value

Mean Value

Median Value

# Acute / Chronic Violations

% Acute/ Chronic Violations

>1 Acute / Chronic Violation

Assessment Type

Support Level

10340001

6

Aluminum

9 / 2

1.1

0.412

0.22

0 / 0

0% / 0%

No

Evaluated

Full

10340001

6

Arsenic

9 / 2

10

5.6

6.1

0 / 0

0% / 0%

No

Evaluated

Full

10340001

6

Cadmium

9 / 2

0.025

0.025

0.025

0 / 0

0% / 0%

No

Evaluated

Full

10340001

6

Chromium

9 / 2

1.2

0.85

0.85

0 / 0

0% / 0%

No

Evaluated

Full

10340001

6

Copper

9 / 2

3

1.11

0.83

0 / 0

0% / 0%

No

Evaluated

Full

10340001

6

Lead

9 / 2

0.16

0.064

0.07

0 / 0

0% / 0%

No

Evaluated

Full

10340001

6

Nickel

9 / 2

3.3

2.5

2.3

0 / 0

0% / 0%

No

Evaluated

Full

10340001

6

Selenium

9 / 2

2.2

1.53

1.5

0 / 0

0% / 0%

No

Evaluated

Full

10340001

6

Zinc

9 / 2

2.9

1.65

1.6

0 / 0

0% / 0%

No

Evaluated

Full


Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/Thermal

BM Sample Gear

BMIBI score

BMIBI Class

47c BMIBI BIT

BMIBI Pass/ Fail

285

8/15/16

1095

47c

MS/WW

Hess

86

Excellent

70

Pass

285

9/8/14

1095

47c

MS/WW

Float ArtSub

27

Poor

52

Fail

285

9/4/13

1095

47c

MS/WW

ArtSub

50

Fair

52

Fail

Overall Assessment:

Community

Assessment Type

Assessment Result

Support Level

Earned IR Category

Actual IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (1/3)

Partial

3bu

3bu

Assessment is evaluated because it used a site with a drainage area larger than the calibrated range.


Class HH – Fish Tissue Sampling:

Site ID

Date

Species Name

Biopart

# in sample

chlordane result

chlordane violation (>0.6)?

PCBs result

PCBs violation (>0.2)?

Hg result

Hg violation (>0.3)?

Assessment Type

Support Level

61

9/22/14

smallmouth bass

plug

4

0.270

No

Monitored

Full

61

9/12/12

smallmouth bass

plug

5

0.464

Yes

Evaluated

Partial

61

9/12/12

channel catfish

fillet

5

<0.03

No

0.09

No

0.172

No

Evaluated

Full

Although the 2014 fish tissue sampling result was “fully supported”, de-listing a Category 5a mercury impairment requires two sample results less than the 0.3 ppm advisory threshold. Additional fish tissue sampling is recommended for this segment.


Class HH-F - Toxic Parameters:

Site ID

Data Source ID

Parameter Name

# Samples / # Years

Maximum Value

Mean Value

Median Value

Number of Non - Detects

Mean Value > Criterion or MCL

Assessment Type

Support Level

10340001

6

Cadmium

9 / 2

0.025

0.025

0.025

9

No

All Non-Detect

Full

10340001

6

Chromium

9 / 2

1.2

0.85

0.85

0

No

Evaluated

Full

10340001

6

Copper

9 / 2

3

1.11

0.83

0

No

Evaluated

Full

10340001

6

Nickel

9 / 2

3.3

2.5

2.3

0

No

Evaluated

Full

10340001

6

Selenium

9 / 2

2.2

1.53

1.5

0

No

Evaluated

Full

10340001

6

Zinc

9 / 2

2.9

1.65

1.6

0

No

Evaluated

Full

Monitoring and Methods
Assessment Key Dates
9/22/2014 Fish Tissue Monitoring
8/15/2016 Biological Monitoring
1/7/2016 Fixed Monitoring Start Date
12/11/2018 Fixed Monitoring End Date
8/7/2012 Biological Monitoring
9/4/2013 Biological Monitoring
9/8/2014 Biological Monitoring
9/12/2012 Fish Tissue Monitoring
Methods
150 Monitoring data more than 5 years old
230 Fixed station physical/chemical (conventional plus toxic pollutants)
260 Fish tissue analysis
315 Regional reference site approach
320 Benthic macroinvertebrate surveys
420 Indicator bacteria monitoring