Iowa DNR
ADBNet

Water Quality Assessments

Impaired Waters List

Little Sioux River IA 06-LSR-1570

from Highway 3 (S26 T92N R40W Cherokee Co.) to confluence with Waterman Cr. in S26 T94N R39W O'Brien Co.

Assessment Cycle
2024
Release Status
Pending
Data Collection Period
Overall IR Category
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Stable
Created
11/1/2023 8:13:03 AM
Updated
12/22/2023 9:43:19 AM
Assessment conducted in accordance with Iowa's 2024 IR methodology.
Use Support
Class A1
Not Supported
Bacteria: Indicator Bacteria- E. coli
Support Level
Not Supported
Impairment Code
5a - Pollutant-caused impairment. TMDL needed.
Cause Magnitude
Slight
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2004
Impairment Rationale
Single-sample maximum criterion exceeded in significantly > 10% of samples
Data Source
Ambient monitoring: Iowa DNR-rivers
TMDL Priority
Tier III
Class BWW1
WINOFI
Biological: low fish & invert IBIs- cause unknown
Support Level
Water in Need of Further Investigation (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
N/A
Cycle Added
2022
Impairment Rationale
Low Biotic Index
Data Source
Beach monitoring: Iowa DNR WQMA
Class HH
Fully Supported
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class A1 use was assessed as “not supported” due to violations of the state water quality criteria for indicator bacteria (E. coli). The Class BWW1 use was assessed as "WINOFI" based on biological sampling data. The Class HH use was assessed as "fully supported" based on water quality monitoring 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 2020-2022

10180001

Little Sioux River near Larrabee

Iowa DNR

6

BIO

See Below

938

Little Sioux River

Larrabee

Iowa DNR

6

BIO

See Below

1267

Little Sioux River

Cherokee (REMAP #404)


Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2020/ 2021/2022)

2020 Geometric Mean

2021 Geometric Mean

2022 Geometric Mean

Violates Annual Geometric Mean?

# 2020 SSM violations / SSM Violations needed for impairment

# 2021 SSM violations / SSM Violations needed for impairment

# 2022 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

10180001

6

8/8/7

232

212

56

YES

4 / 3

5 / 3

2 / 3

YES

Mon

Not


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

10180001

6

36 / 3

7

8.6

8

0

7

NO

Mon

Full


Class BWW1 - Binomial 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

10180001

6

Chloride

36 / 3

14

33

24

NA

0 / 0

7

NO

Mon

Full

10180001

6

Dissolved Oxygen

36 / 3

6

13.7

9.6

0

NA / NA

7

NO

Mon

Full

10180001

6

pH

36 / 3

7

8.6

8

0

NA / NA

7

NO

Mon

Full

10180001

6

Sulfate

36 / 3

26

100

73

0

NA / NA

7

NO

Mon

Full

10180001

6

Temperature

36 / 3

0

27.6

11.4

0

NA / NA

7

NO

Mon

Full


Class BWW1 - 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

10180001

6

Ammonia

36 / 3

0.41

0.05

0.02

0 / 0

NO

Mon

Full

10180001

6

Cadmium

20 / 3

0.5

0.5

0.5

0 / 0

NO

Mon

Full

10180001

6

Chromium

20 / 3

12

1.32

0.64

0 / 1

NO

Mon

Full

10180001

6

Lead

20 / 3

1

0.91

1

0 / 0

NO

Mon

Full

10180001

6

Nickel

20 / 3

3.3

2.2

2.1

0 / 0

NO

Mon

Full

10180001

6

Selenium

18 / 2

3

1.6

2

0 / 0

NO

Mon

Full

10180001

6

Silver

20 / 3

1

0.902

1

0 / 0

NO

Mon

Full

10180001

6

Zinc

20 / 3

2.5

0.9

0.5

0 / 0

NO

Mon

Full


Class BWW1 - Biological Sampling:


Benthic Macroinvertebrates:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

BM Sample Gear

BMIBI score

BMIBI Class

47a BMIBI BIT

BMIBI Pass/Fail

938

8/14/21

1848.0

47a

MO

Floating Art Sub

19

Poor

54

Fail

1267

9/22/20

2180.0

47a

MO

Floating Art Sub

53

Fair

54

Fail

938

7/18/17

1848.0

47a

MO

Hess

74

Good

54

Pass


Fish:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

Riffle Stream?

FIBI score

FIBI Class

47a FIBI BIT

FIBI Pass/Fail

1267

9/22/20

2180.0

47a

MO

NA

24

Poor

43

Fail


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (1/3)

WINOFI

Fish

Evaluated

Fail (0/1)

WINOFI

Assessment was evaluated because the drainage areas

Overall

Evaluated

Fail

WINOFI

3bu

of the sites were greater than the calibrated range.


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

10180001

6

Selenium

18 / 2

3

1.6

2

7

NO

Mon

Full

Monitoring and Methods
Assessment Key Dates
1/8/2020 Monitoring Start
12/14/2022 Monitoring End
7/18/2017 Biological Monitoring
9/22/2020 Biological Monitoring
8/24/2021 Biological Monitoring
Methods
200 Physical/Chemical Monitoring
315 Regional reference site approach
320 Benthic macroinvertebrate surveys
330 Fish surveys
420 Indicator bacteria monitoring