Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Winnebago River IA 02-WIN-831

from confluence with Pike Run (S25 T99N R24W Winnebago Co.) to the Iowa/Minnesota state line

Cycle
2024
Release Status
Final
Overall IR
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
11/1/2023 8:12:35 AM
Updated
12/29/2023 1:29:12 PM
Use Support
Class A1
Recreation - Primary contact
WINOFI
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
Slight
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2022
Impairment Rationale
Geometric mean criterion exceeded
Data Source
Ambient monitoring: adjacent state
Class BWW2
Aquatic Life - Warm Water Type 2
Not Supported
Support Level
Not Supported
Impairment Code
5b-v - Biological - verified
Cause Magnitude
Moderate
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2004
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 “WINOFI” due to violations of Iowa water quality criteria for indicator bacteria (E. coli).The Class BWW2 use was assessed as "not supported" based on biological sampling data. All other designated uses were "not assessed."

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

MNPCA

15

WQ

CY 2019-2020

99990106

Lime Creek

Iowa DNR

6

BIO

See Below

30

Winnebago River

Lande Access – Lake Mills

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

99990106

15

0/5/6

NA

193

176

YES

NA

1 / NA

2 / NA

NA

Evaluated

WINOFI

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

99990106

15

23 / 2

7

8.5

7.9

0

5

NO

Monitored

Full

Class BWW2 - 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

99990106

15

Dissolved Oxygen

23 / 2

4.7

13.4

8.4

2

NA / NA

5

NO

Monitored

Full

99990106

15

pH

23 / 2

7

8.5

7.9

0

NA / NA

5

NO

Monitored

Full

99990106

15

Temperature

23 / 2

9.924

27

20.834

0

NA / NA

5

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

47b BMIBI BIT

BMIBI Pass/Fail

30

9/2/20

112.5

47b

MS

Art Sub

51

Fair

62

Fail

30

9/28/15

112.5

47b

MS

Art Sub

57

Good

62

Fail


Fish:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

Riffle Stream?

FIBI score

FIBI Class

47b FIBI BIT

FIBI Pass/Fail

30

9/2/20

112.5

47b

MS

No

27

Fair

32

Fail

30

9/28/15

112.5

47b

MS

No

24

Poor

32

Fail


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (0/2)

Not

Fish

Evaluated

Fail (0/2)

Not

5bv

Assessment was evaluated because it included samples not collected in

Overall

Evaluated

Fail

Not

the last five years.


Monitoring and Methods
Assessment Key Dates
9/2/2020
Biological Monitoring
9/28/2015
Biological Monitoring
5/23/2019
Monitoring Start
9/24/2020
Monitoring End
Methods
150
Monitoring data more than 5 years old
200
Physical/Chemical Monitoring
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys
380
Quantitative physical habitat assessment