Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Prairie Creek IA 02-CED-510

from confluence with Mud Cr. (S21 T82N R9W Benton Co.) to confluence with unnamed tributary in S13 T83N R12W Benton Co.

Cycle
2022
Release Status
Final
Overall IR
3 - Insufficient data exist to determine whether any designated uses are met.
Trend
Unknown
Created
12/30/2021 10:56:20 AM
Updated
1/13/2022 6:14:03 AM
Use Support
Class A1
Recreation - Primary contact
WINOFI
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
Moderate
Status
New
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2022
Impairment Rationale
Geometric mean criterion exceeded
Data Source
Watershed project monitoring
Class BWW2
Aquatic Life - Warm Water Type 2
WINOFI
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
Moderate
Status
Continuing
Source
Agriculture: Animal Feeding Operations
Source Confidence
N/A
Cycle Added
2004
Impairment Rationale
Pollutant-caused fish kill
Data Source
Fish kill investigation: Iowa DNR
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The presumptive Class A1 use was assessed as “WINOFI” based on levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW2 use was assessed as "WINOFI" due to a fish kill investigation.

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

CRWQ

23

WQ

CY 2018-2020

99990084

Prairie Creek

CRWQ

23

WQ

CY 2018-2020

99990085

Prairie Creek

CRWQ

23

WQ

CY 2018-2020

99990086

Prairie Creek

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

99990084

23

5/5/5

1219

343

434

YES

4 / NA

3 / NA

3 / NA

NA

Evaluated

WINOFI

99990085

23

5/5/5

2394

733

1430

YES

5 / NA

5 / NA

5 / NA

NA

Evaluated

WINOFI

99990086

23

5/5/5

1831

804

444

YES

5 / NA

5 / NA

5 / NA

NA

Evaluated

WINOFI

Presumptive 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

99990084

23

15 / 3

7.25

8.17

7.76

0

4

NO

Monitored

Full

99990085

23

15 / 3

7.4

8.2

7.9

0

4

NO

Monitored

Full

99990086

23

15 / 3

7.6

8.2

8

0

4

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

99990084

23

Chloride

15 / 3

11.8

29.8

17.9

NA

0 / 0

4

NO

Monitored

Full

99990085

23

Chloride

15 / 3

14.4

44.4

19.4

NA

0 / 0

4

NO

Monitored

Full

99990086

23

Chloride

15 / 3

14.3

39.3

19

NA

0 / 0

4

NO

Monitored

Full

99990084

23

Dissolved Oxygen

15 / 3

2.4

10.3

7.7

1

NA / NA

4

NO

Monitored

Full

99990085

23

Dissolved Oxygen

15 / 3

7.2

14.8

9.4

0

NA / NA

4

NO

Monitored

Full

99990086

23

Dissolved Oxygen

15 / 3

6.1

11.4

8.5

0

NA / NA

4

NO

Monitored

Full

99990084

23

pH

15 / 3

7.25

8.17

7.76

0

NA / NA

4

NO

Monitored

Full

99990085

23

pH

15 / 3

7.4

8.2

7.9

0

NA / NA

4

NO

Monitored

Full

99990086

23

pH

15 / 3

7.6

8.2

8

0

NA / NA

4

NO

Monitored

Full

99990084

23

Sulfate

15 / 3

14

34.6

23.6

0

NA / NA

4

NO

Monitored

Full

99990085

23

Sulfate

15 / 3

17.8

42.6

26

0

NA / NA

4

NO

Monitored

Full

99990086

23

Sulfate

15 / 3

20.4

53

32.4

0

NA / NA

4

NO

Monitored

Full

99990084

23

Temperature

15 / 3

8.4

21.8

16.6

0

NA / NA

4

NO

Monitored

Full

99990085

23

Temperature

15 / 3

9.3

23.4

18

0

NA / NA

4

NO

Monitored

Full

99990086

23

Temperature

15 / 3

9.6

26.3

19

0

NA / NA

4

NO

Monitored

Full


Class BWW2 – Fishkill Investigation:

The Class BWW2 use previously resided in Category 4d based on the assessment developed for the 2012 fish kill. Because no additional fish kills were reported in this segment for at least five years post fish kill (2017), the Category for the fish kill assessment was changed from 4d to 3b (potentially impaired). DNR believes that any impact from the fish kill from which the impairment was based has likely dissipated. If no additional fish kills are reported in the segment for an additional five-year period (2022), the Category will be changed from 3b to 3a (water not assessed).

Details about the 2012 fish kill can be found here: https://programs.iowadnr.gov/fishkill/Events/854

Monitoring and Methods
Assessment Key Dates
10/25/2012
Fish Kill
5/16/2018
Non-fixed Monitoring Start Date
9/29/2020
Non-fixed Monitoring End Date
Methods
120
Surveys of fish and game biologists/other professionals
140
Incidence of spills and/or fish kills
150
Monitoring data more than 5 years old
220
Non-fixed station physical/chemical monitoring (conventional pollutant only)
420
Indicator bacteria monitoring
860
Other Agencies/Organizations provided monitoring data