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
2022
Release Status
Final
Cycle Period
2018 - 2020
Overall IR Category
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
12/27/2021 9:06:10 AM
Updated
1/26/2022 3:37:28 PM
Assessment conducted in accordance with Iowa's 2022 IR methodology
Use Support
Class A1
Not Supported
Bacteria: Indicator Bacteria- E. coli
Support Level
Not 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
Not Supported
Biological: low aquatic macroinvertebrate IBI
Support Level
Not 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
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The presumptive Class A1 use was assessed as "not supported" due to levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW2 use was assessed as "not supported" based on biological sampling data.

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

WQ

CY 2018-2020

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 per Year (2018/ 2019/2020)

2018 Geometric Mean

2019 Geometric Mean

2020 Geometric Mean

Violates Annual Geometric Mean?

# 2018 SSM violations / SSM Violations needed for impairment

# 2019 SSM violations / SSM Violations needed for impairment

# 2020 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

10500001

6

6/7/6

707

394

739

YES

4 / NA

5 / 3

6 / NA

YES

Monitored

Not

Class A - 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

10500001

6

36 / 3

7.2

8.4

8

0

7

NO

Monitored

Full

Class BWW2 - 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

10500001

6

Ammonia

36 / 3

0.02

0.42

0.05

NA

0 / 0

7

NO

Monitored

Full

10500001

6

Chloride

36 / 3

6.4

44

20.9

NA

0 / 0

7

NO

Monitored

Full

10500001

6

Dissolved Oxygen

36 / 3

5.9

14.2

10

0

NA / NA

7

NO

Monitored

Full

10500001

6

pH

36 / 3

7.2

8.4

8

0

NA / NA

7

NO

Monitored

Full

10500001

6

Sulfate

36 / 3

4

58

22

0

NA / NA

7

NO

Monitored

Full

10500001

6

Temperature

36 / 3

0

24.6

10.7

0

NA / NA

7

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

>1 Acute / Chronic Violation

Assessment Type

Support Level

10500001

6

Aluminum

14 / 3

11

1.626

0.455

0 / 0

NO

Monitored

Full

10500001

6

Arsenic

13 / 3

2.7

1.6

1.6

0 / 0

NO

Monitored

Full

10500001

6

Cadmium

13 / 3

0.05

0.03

0.02

0 / 0

NO

Monitored

Full

10500001

6

Chromium

13 / 3

1.5

1

1

0 / 0

NO

Monitored

Full

10500001

6

Lead

13 / 3

0.18

0.11

0.12

0 / 0

NO

Monitored

Full

10500001

6

Nickel

13 / 3

4.3

3.2

3.1

0 / 0

NO

Monitored

Full

10500001

6

Silver

13 / 3

0.025

0.025

0.025

0 / 0

NO

Monitored

Full

10500001

6

Zinc

13 / 3

2.7

1.6

1.5

0 / 0

NO

Monitored

Full


Class BWW2 - Biological Sampling:


Benthic Macroinvertebrates:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

BM Sample Gear

BMIBI score

BMIBI Class

47f BMIBI BIT

BMIBI Pass/Fail

919

7/19/19

395

47f

MS

Floating Art Sub

65

Good

51

Pass

919

10/14/16

395

47f

MS

Floating Art Sub

47

Fair

51

Fail

Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (1/2)

Not

Assessment was evaluated because the BMIBI assessment was inconclusive.

Overall

Evaluated

Fail

Not

5bv

The impairment remains until a monitored assessment shows improvement.



Monitoring and Methods
Assessment Key Dates
7/19/2019 Biological Monitoring
1/4/2018 Fixed Monitoring Start Date
12/2/2020 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)