Iowa DNR
ADBNet

Water Quality Assessments

Impaired Waters List

Walnut Creek IA 03-SSK-953

mouth (S5 T82N R23W Story Co.) to confluence with unnamed tributary in SE 1/4 S34 T83N R24W Story Co.

Assessment Cycle
2020
Release Status
Final
Cycle Period
2016 - 2018
Overall IR Category
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
9/9/2020 3:04:25 PM
Updated
10/16/2020 10:50:29 AM
Assessment conducted in accordance with Iowa's 2020 IR methodology
Use Support
Class A1
Not Assessed
Class BWW2
Partially Supported
Biological: low fish IBI
Support Level
Partially Supported
Impairment Code
5b-t - Biological - tentative
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
General Use
Not Assessed
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class BWW2 use remains assessed as "partially supported" based on biological sampling data. All other designated uses were "not assessed".

Assessment Explanation

Sources of Data:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

BIO

See Below

210

Walnut Creek

Ames

Iowa DNR

6

BIO

See Below

859

Walnut Creek

Huxley


Presumptive Class A1 - No Data


Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/Thermal

BM Sample Gear

BMIBI score

BMIBI Class

47b BMIBI BIT

BMIBI Pass/ Fail

859

8/22/11

18

47b

MS/WW

LowFlow ArtSub

48

Fair

62

Fail

210

7/19/11

13

47b

MS/WW

Surb

68

Good

62

Pass

210

7/17/07

13

47b

MS/WW

Hess

77

Excellent

62

Pass

Fish:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/Thermal

Riffle Stream?

FIBI score

FIBI Class

47b FIBI BIT

FIBI Pass/ Fail

859

7/20/11

18

47b

MS/WW

No

17

Poor

32

Fail

210

7/19/11

13

47b

MS/WW

Yes

36

Fair

53

Fail

210

7/17/07

13

47b

MS/WW

Yes

29

Fair

53

Fail

Overall:

Community

Assessment Type

Assessment Result

Support Level

Earned IR Category

Actual IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Pass (2/3)

Full

Fish

Evaluated

Fail (0/3)

Partial

Overall

Evaluated

Fail

Partial

3bc

5bt

Assessment is evaluated because it included samples not collected in the last five years.

Monitoring and Methods
Assessment Key Dates
7/17/2007 Biological Monitoring
7/19/2011 Biological Monitoring
7/20/2011 Biological Monitoring
Methods
150 Monitoring data more than 5 years old
315 Regional reference site approach
320 Benthic macroinvertebrate surveys
330 Fish surveys