Iowa DNR
ADBNet

Water Quality Assessments

Impaired Waters List

Ioway Creek IA 03-SSK-954

mouth (S12 T83N R24W Story Co.) to confluence with unnamed tributary in NW 1/4 S9 T85N R25W Boone Co.

Assessment Cycle
2020
Release Status
Final
Cycle Period
2016 - 2018
Overall IR Category
3 - Insufficient data exist to determine whether any designated uses are met.
Trend
Unknown
Created
9/10/2020 7:48:57 AM
Updated
1/13/2021 2:04:27 PM
Assessment conducted in accordance with Iowa's 2020 IR methodology
Use Support
Class A1
WINOFI
Bacteria: Indicator Bacteria- E. coli
Support Level
Water in Need of Further Investigation (WINOFI)
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
Moderate
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2018
Impairment Rationale
Geometric mean criterion exceeded
Data Source
Special project/study
Class BWW2
WINOFI
Biological: low aquatic macroinvertebrate IBI
Support Level
Water in Need of Further Investigation (WINOFI)
Impairment Code
3b-c - Use potentially biologically impaired based on calibrated IBI metrics.
Cause Magnitude
Slight
Status
New
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2020
Impairment Rationale
Low Biotic Index
Data Source
Biological monitoring: Iowa DNR WQMA
General Use
Not Assessed
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class A1 use was assessed as "not supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW2 use was assessed as "partially supported" based on biological sampling data.

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

290

Squaw Creek

Ames – Veenker Golf Course – REMAP #9

Story Co.

NA

WQ

CY 2016-2018

NA

Squaw Creek

Site monitored by Prairie River Watershed Group and Story Co. Conservation


Class A1 - Indicator Bacteria:

# Samples / # Years

2016 Geometric Mean

2017 Geometric Mean

2018 Geometric Mean

Annual Geometric Mean Violation

# Violations

% Violations

Significantly >10% Violations

Assessment Type

Support Level

48 / 3

1825

1717

2280

Yes

46

96%

Yes

Evaluated

Not

The bacteria samples were collected by the Prairie Rivers Watershed Group and Story County Conservation with the analyses conducted by the City of Ames. Since the data were not collected under a DNR-approved quality assurance plan, the assessment was considered "evaluated" instead of "monitored". According to Iowa DNR’s assessment/listing methodology, impairments based on “evaluated” assessments are of lesser confidence and are not appropriate for Section 303(d) listing (Category 5 of the Integrated Report). The Iowa DNR does, however, consider these impairments as appropriate for listing under Category 3b of the Integrated Report (waters potentially impaired and in need of further investigation).


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

290

9/22/17

194

47b

MS/WW

Hess

53

Fair

62

Fail

Fish:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/Thermal

Riffle Stream?

FIBI score

FIBI Class

47b FIBI BIT

FIBI Pass/ Fail

290

9/22/17

194

47b

MS/WW

No

48

Fair

32

Pass

Overall:

Community

Assessment Type

Assessment Result

Support Level

Earned IR Category

Actual IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (0/1)

Partial

When the BMIBI UAV of 8 points was applied, this site failed the BMIBI BIT by 1 point.

Fish

Evaluated

Pass (1/1)

Full

Overall

Evaluated

Fail

Partial

3bc

3bc

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


Monitoring and Methods
Assessment Key Dates
9/22/2017 Biological Monitoring
4/27/2016 Non-fixed Monitoring Start Date
10/12/2016 Non-fixed Monitoring End Date
Methods
315 Regional reference site approach
320 Benthic macroinvertebrate surveys
330 Fish surveys
420 Water column surveys (e.g. fecal coliform)
860 Other Agencies/Organizations provided monitoring data