Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

East Nishnabotna River IA 05-NSH-1816

from Page/Montgomery Co. line to state Highway 48 bridge approximately 1.5 miles north of Red Oak at east line of S8 T72N R38W Montgomery Co.

Cycle
2022
Release Status
Final
Overall IR
2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
Trend
Unknown
Created
1/3/2022 7:06:59 AM
Updated
1/14/2022 12:57:24 PM
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class BWW1
Aquatic Life - Warm Water Type 1
WINOFI
Impairment Code
3b-u - Use potentially biologically impaired based on uncalibrated IBI metrics.
Cause Magnitude
Slight
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2010
Impairment Rationale
Low Biotic Index
Data Source
Biological monitoring: Iowa DNR WQMA
Class HH
Human Health -
Fully Supported
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class BWW1 use was assessed as "WINOFI" based on biological sampling data. The Class HH (fish consumption) use was assessed as "fully supported" based on fish tissue sampling data. All other designated uses were "not assessed."

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

BIO

See Below

680

East Nishnabotna River

Red Oak – DS1

Iowa DNR

6

BIO

See Below

681

East Nishnabotna River

Red Oak – US1

Iowa DNR

6

FT

See Below

139

East Nishnabotna River

Near Red Oak


Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/ Thermal

BM Sample Gear

BMIBI score

BMIBI Class

47e BMIBI BIT

BMIBI Pass/ Fail

680

10/12/07

895

47e

MO/WW

ArtSub

46

Fair

54

Fail

681

10/12/07

891

47e

MO/WW

ArtSub

42

Fair

54

Fail

680

9/6/07

895

47e

MO/WW

ArtSub

50

Fair

54

Fail


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (0/3)

WINOFI

3bu

Assessment was evaluated because the drainage areas of the sample sites were larger than the calibrated range.


Class HH - Fish Tissue Sampling:

Site ID

Biopart

Year

Species

# in sample / # of samples

Avg Length (cm)

(Avg) Hg (ppm)

Chlordane (ppm)

Sum PCBs (ppm)

139

fillet

2011

channel catfish

5

44.2

0.039

0.037

0.09

139

tissue plug

2020

channel catfish

10

49.4

0.093

139

tissue plug

2012

freshwater drum

5

59.0

0.216

Support Level

Full

Monitoring and Methods
Assessment Key Dates
9/6/2007
Biological Monitoring
10/12/2007
Biological Monitoring
8/18/2011
Fish Tissue Monitoring
7/31/2012
Fish Tissue Monitoring
7/1/2020
Fish Tissue Monitoring
Methods
150
Monitoring data more than 5 years old
260
Fish tissue analysis
315
Regional reference site approach
320
Benthic macroinvertebrate surveys