Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Floyd River IA 06-FLO-1554

from city of Alton (north line S11 T94N R44W Sioux Co.) to confluence with North Fork Floyd R. in S9 T97N R41W O'Brien Co.

Cycle
2024
Release Status
Final
Overall IR
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
11/1/2023 8:12:26 AM
Updated
2/6/2024 8:31:45 AM
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class BWW2
Aquatic Life - Warm Water Type 2
Not Supported
Support Level
Not Supported
Impairment Code
5b-t - Biological - tentative
Cause Magnitude
Moderate
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2004
Impairment Rationale
Low Biotic Index
Data Source
Biological monitoring: Iowa DNR WQMA
TMDL Priority
Tier IV
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class BWW2 use was assessed as “not supported” based on biological 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

355

Floyd River

Sanborn – REMAP #67

Iowa DNR

6

BIO/WQ

See Below

364

Floyd River

Alton – REMAP #85


Presumptive Class A1 – No Data


Class BWW2 - Biological Sampling:


Benthic Macroinvertebrates:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

BM Sample Gear

BMIBI score

BMIBI Class

47a BMIBI BIT

BMIBI Pass/Fail

355

8/18/20

43.9

47a

MO

Floating Art Sub

26

Poor

54

Fail

364

8/17/20

260.6

47a

MO

Floating Art Sub

62

Good

54

Pass


Fish:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

Riffle Stream?

FIBI score

FIBI Class

47a FIBI BIT

FIBI Pass/Fail

355

8/18/20

43.9

47a

MO

NA

28

Fair

43

Fail

364

8/17/20

260.6

47a

MO

NA

36

Fair

43

Fail


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (1/2)

Not

Fish

Evaluated

Fail (0/2)

Not

Assessment was evaluated because the samples used to

Overall

Evaluated

Fail

Not

5bt

complete the assessment were collected in a single year.


Class BWW2- Continuous DO Monitoring:

Site ID

Data Source ID

# Days Monitoring (2020)

DO Criteria Type

# 2020 violations / Violations needed for impairment

Violates Annual Significantly >10% Rule?

Assessment Type

Support Level

24 hr

0/5

No

355

6

21

16 hr

0/5

No

Monitored

Full

24 hr

0/5

No

364

6

19

16 hr

0/5

No

Monitored

Full

Monitoring and Methods
Assessment Key Dates
8/18/2020
Biological Monitoring
8/17/2020
Biological Monitoring
7/29/2020
Monitoring Start
8/17/2020
Monitoring End
Methods
200
Physical/Chemical Monitoring
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys