Iowa DNR
ADBNet

Water Quality Assessments

Impaired Waters List

Indian Creek IA 03-SSK-943

mouth (S32 T80N R20W Jasper Co.) to confluence of East Indian and West Indian creeks in S16 T82N R22W Story Co.

Assessment Cycle
2020
Release Status
Final
Cycle Period
2016 - 2018
Overall IR Category
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
9/9/2020 2:31:02 PM
Updated
10/16/2020 10:46:10 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
5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.
Cause Magnitude
Moderate
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 BWW2
Partially Supported
Biological: low aquatic macroinvertebrate IBI
Support Level
Partially Supported
Impairment Code
5b-v - Biological - verified
Cause Magnitude
Moderate
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2016
Impairment Rationale
Low Biotic Index
Data Source
Biological monitoring: Iowa DNR WQMA
TMDL Priority
Tier IV
General Use
Not Assessed
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The presumptive Class A1 use was assessed as "partially supported" due to levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW2 use was assessed as "partially supported" based on biological 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

10500001

Indian Creek near Colfax

Iowa DNR

6

BIO

See Below

919

Indian Creek

Colfax


Presumptive 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

10500001

6

18 / 3

305.47

209.93

706.83

Yes

9

50%

Yes

Monitored

Partial


Presumptive 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

10500001

6

36 / 3

8.5

8.1

8.2

0

0%

No

Monitored

Full


Class BWW2 - 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

10500001

6

Ammonia

36 / 3

0.95

0.07

0.02

0 / 0

0% / 0%

No

Monitored

Full

10500001

6

Chloride

36 / 3

44

21.6

19

0 / 0

0% / 0%

No

Monitored

Full

10500001

6

Dissolved oxygen

36 / 3

14.2

10.2

9.8

NA / 0

NA / 0%

No

Monitored

Full

10500001

6

pH

36 / 3

8.5

8.1

8.2

0 / NA

0% / NA

No

Monitored

Full

10500001

6

Sulfate

36 / 3

58

23

19

0 / NA

0% / NA

No

Monitored

Full

10500001

6

Temperature

36 / 3

31

12

13

0 / 0

0% / 0%

No

Monitored

Full


Class BWW2 - 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

10500001

6

Aluminum

9 / 2

11

2.243

0.5

0 / 0

0% / 0%

No

Evaluated

Full

10500001

6

Arsenic

9 / 2

2.2

1.8

1.9

0 / 0

0% / 0%

No

Evaluated

Full

10500001

6

Cadmium

9 / 2

0.05

0.028

0.025

0 / 0

0% / 0%

No

Evaluated

Full

10500001

6

Chromium

9 / 2

1.2

0.81

0.89

0 / 0

0% / 0%

No

Evaluated

Full

10500001

6

Copper

9 / 2

3

1.19

0.97

0 / 0

0% / 0%

No

Evaluated

Full

10500001

6

Lead

9 / 2

0.09

0.061

0.07

0 / 0

0% / 0%

No

Evaluated

Full

10500001

6

Nickel

9 / 2

4.1

3

3

0 / 0

0% / 0%

No

Evaluated

Full

10500001

6

Selenium

9 / 2

2.2

1.31

1.3

0 / 0

0% / 0%

No

Evaluated

Full

10500001

6

Zinc

9 / 2

2.7

1.12

1

0 / 0

0% / 0%

No

Evaluated

Full


Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/Thermal

BM Sample Gear

BMIBI score

BMIBI Class

47f BMIBI BIT

BMIBI Pass/ Fail

919

10/14/16

395

47f

MS/WW

Float ArtSub

47

Fair

51

Fail

919

9/25/13

395

47f

MS/WW

ArtSub

43

Fair

51

Fail

Overall:

Community

Assessment Type

Assessment Result

Support Level

Earned IR Category

Actual IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (0/2)

Partial

3bc

5bv

Assessment is evaluated because it included samples not collected in the last five years.

Monitoring and Methods
Assessment Key Dates
9/25/2013 Biological Monitoring
1/7/2016 Fixed Monitoring Start Date
12/5/2018 Fixed Monitoring End Date
10/14/2016 Biological Monitoring
Methods
230 Fixed station physical/chemical (conventional plus toxic pollutants)
315 Regional reference site approach
320 Benthic macroinvertebrate surveys
420 Water column surveys (e.g. fecal coliform)
150 Monitoring data more than 5 years old