Iowa DNR
Iowa DNR

ADBNet

Water Quality Assessments
Impaired Waters List

Dry Run Creek IA 01-UIA-6552

from west line of section (T98N R9W Sec36) to headwaters (T98N R9W Sec29) Winneshiek Co.

Overall IR
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
1/11/2022 1:34:36 PM by
Updated
1/11/2022 1:37:14 PM by
Use Support
Class A1
Recreation - Primary contact
Not Supported
Support Level
Not Supported
Impairment Code
5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.
Cause Magnitude
High
303(d) Listing Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2014
Impairment Rationale
Geometric mean criterion exceeded
Data Source
Special project/study: Iowa DNR
TMDL Priority
Tier III
Class BWW1
Aquatic Life - Warm Water Type 1
Fully Supported
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 exceeded state water quality criteria. The presumptive Class BWW1 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 2010-2011

15960026

Dry Run Creek Watershed Site 14

Iowa DNR

6

WQ

CY 2010

15960027

Dry Run Creek Watershed Site 15

Presumptive Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples / # Years

2010 Geometric Mean

2011 Geometric Mean

Annual Geometric Mean Violation

# Violations

% Violations

Significantly >10% Violations

Assessment Type

Support Level

15960026

6

28 / 2

1708

1985

Yes

25

89%

Yes

Evaluated

Not

15960027

6

13 / 1

1279

NA

Yes

11

85%

Yes

Evaluated

Not

The monitoring conducted as part of this watershed study included sampling for indicator bacteria (E. coli) immediately (within 24 hours) following rainfall runoff events. About half the samples in each of 2010 and 2011 were collected under such conditions. See the following journal article for more information: Wittman et al. 2013. Evaluation of land use and water quality in an agricultural watershed in the USA indicates multiple sources of bacterial impairment. Environ. Monit. Assess. (2013) 185:10395-10429.


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

15960026

6

27 / 2

8.4

7.8

7.9

1

4%

No

Evaluated

Full

15960027

6

12 / 1

7.8

7.5

7.5

0

0%

No

Evaluated

Full


Presumptive Class BWW1 - 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

15960026

6

Ammonia

26 / 2

0.16

0.06

0.05

0 / 0

0% / 0%

No

Evaluated

Full

15960026

6

Dissolved oxygen

32 / 2

13.1

9.3

9.3

NA / 1

NA / 3%

No

Evaluated

Full

15960026

6

pH

27 / 2

8.4

7.8

7.9

1 / NA

4% / NA

No

Evaluated

Full

15960026

6

Temperature

32 / 2

24.6

16.2

16.6

0 / 0

0% / 0%

No

Evaluated

Full

15960027

6

Ammonia

11 / 1

0.05

0.05

0.05

0 / 0

0% / 0%

No

Evaluated

Full

15960027

6

Dissolved oxygen

13 / 1

10.6

7.3

6.9

NA / 1

NA / 8%

No

Evaluated

Full

15960027

6

pH

12 / 1

7.8

7.5

7.5

0 / NA

0% / NA

No

Evaluated

Full

15960027

6

Temperature

13 / 1

20.6

14.9

15.8

0 / 0

0% / 0%

No

Evaluated

Full

Monitoring and Methods
Assessment Key Dates
4/21/2010
Non-fixed Monitoring Start Date
10/10/2011
Non-fixed Monitoring End Date
Methods
150
Monitoring data more than 5 years old
220
Non-fixed station physical/chemical monitoring (conventional pollutant only)
420
Indicator bacteria monitoring