Iowa DNR
ADBNet

Water Quality Assessments

Impaired Waters List

Wolf Creek IA 02-CED-530

mouth (S29 T87N R11W Black Hawk Co.) to confluence with Twelvemile Cr. in S19 T86N R13W Tama Co.

Assessment Cycle
2020
Release Status
Final
Data Collection Period
Overall IR Category
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
8/31/2020 12:09:03 PM
Updated
10/16/2020 8:51:33 AM
Assessment conducted in accordance with Iowa's 2020 IR methodology
Use Support
Class A1
Presumptive Use
Partially Supported
Bacteria: Indicator Bacteria- E. coli
Support Level
Partially Supported
Impairment Code
5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.
Cause Magnitude
Slight
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 BWW1
Fully Supported
Class HH
Fully Supported
General Use
Not Assessed
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The presumptive Class A1 use was assessed as "partially supported" due to levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW1 use was assessed as "fully supported" based on ambient water quality monitoring data and also on biological sampling data. The Class HH use was assessed as "fully supported" based on ambient water quality monitoring data.

Assessment Explanation

Sources of Data:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

WQ

CY 2016-2018

10070002

Wolf Creek at La Porte City

Iowa DNR

6

BIO

See Below

1154

Wolf Creek

La Porte City - Main Street Bridge


Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples / # Years

2016 Geometric Mean

2017 Geometric Mean

2018 Geometric Mean

Annual Geometric Mean Violation

# Violations

% Violations

Significantly >10% Violations

Assessment Type

Support Level

10070002

6

20 / 3

458.96

580.54

491.6

Yes

15

75%

Yes

Monitored

Partial


Class A - pH:

Site ID

Data Source ID

# Samples / # Years

Maximum Value

Mean Value

Median Value

# Violations

% Violations

Significantly >10% Violations

Assessment Type

Support Level

10070002

6

36 / 3

8.4

8.1

8.2

0

0%

No

Monitored

Full


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

10070002

6

Ammonia

36 / 3

0.16

0.04

0.02

0 / 0

0% / 0%

No

Monitored

Full

10070002

6

Chloride

36 / 3

24

20

20

0 / 0

0% / 0%

No

Monitored

Full

10070002

6

Dissolved oxygen

36 / 3

14.4

10.4

10.4

NA / 0

NA / 0%

No

Monitored

Full

10070002

6

pH

36 / 3

8.4

8.1

8.2

0 / NA

0% / NA

No

Monitored

Full

10070002

6

Sulfate

36 / 3

51

22

20

0 / NA

0% / NA

No

Monitored

Full

10070002

6

Temperature

36 / 3

25.5

11.6

12

0 / 0

0% / 0%

No

Monitored

Full


Class BWW1 - Toxic Parameters:

Site ID

Data Source ID

Parameter Name

# Samples / # Years

Maximum Value

Mean Value

Median Value

# Acute / Chronic Violations

% Acute/ Chronic Violations

>1 Acute / Chronic Violation

Assessment Type

Support Level

10070002

6

Aluminum

9 / 2

4.1

1.673

1.4

0 / 0

0% / 0%

No

Evaluated

Full

10070002

6

Arsenic

9 / 2

1.2

0.83

0.89

0 / 0

0% / 0%

No

Evaluated

Full

10070002

6

Cadmium

9 / 2

0.025

0.025

0.025

0 / 0

0% / 0%

No

Evaluated

Full

10070002

6

Chromium

9 / 2

1.2

0.82

0.94

0 / 0

0% / 0%

No

Evaluated

Full

10070002

6

Copper

9 / 2

0.88

0.52

0.48

0 / 0

0% / 0%

No

Evaluated

Full

10070002

6

Lead

9 / 2

0.25

0.07

0.05

0 / 0

0% / 0%

No

Evaluated

Full

10070002

6

Nickel

9 / 2

2.4

2

2

0 / 0

0% / 0%

No

Evaluated

Full

10070002

6

Selenium

9 / 2

2.3

1.8

1.7

0 / 0

0% / 0%

No

Evaluated

Full

10070002

6

Zinc

9 / 2

3.4

1.51

0.98

0 / 0

0% / 0%

No

Evaluated

Full


Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/Thermal

BM Sample Gear

BMIBI score

BMIBI Class

47c BMIBI BIT

BMIBI Pass/ Fail

1154

8/15/18

326

47c

MS/WW

Floating ArtSub

81

Excellent

52

Pass

Overall Assessment:

Community

Assessment Type

Assessment Result

Support Level

Earned IR Category

Actual IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Pass (1/1)

Full

1

1

Assessment is evaluated because it was based on a single sample.


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

10070002

6

Cadmium

9 / 2

0.025

0.025

0.025

9

No

All Non-Detect

Full

10070002

6

Chromium

9 / 2

1.2

0.82

0.94

0

No

Evaluated

Full

10070002

6

Copper

9 / 2

0.88

0.52

0.48

0

No

Evaluated

Full

10070002

6

Nickel

9 / 2

2.4

2

2

0

No

Evaluated

Full

10070002

6

Selenium

9 / 2

2.3

1.8

1.7

0

No

Evaluated

Full

10070002

6

Zinc

9 / 2

3.4

1.51

0.98

0

No

Evaluated

Full

Monitoring and Methods
Assessment Key Dates
8/15/2018 Biological Monitoring
1/7/2016 Fixed Monitoring Start Date
12/11/2018 Fixed Monitoring End Date
Methods
230 Fixed station physical/chemical (conventional plus toxic pollutants)
315 Regional reference site approach
320 Benthic macroinvertebrate surveys
420 Indicator bacteria monitoring