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
2022
Release Status
Final
Overall IR
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
12/9/2021 12:37:12 PM
Updated
1/25/2022 3:34:14 PM
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
Cycle Added Class Cause Data Source Rationale
2004 Class BWW2 Fish Kill: Caused By Fertilizer Spill Biological monitoring: Iowa DNR fish kill follow-up New data: recovery of fish community from pollutant-caused fish kill
2004 Class BWW2 Fish Kill: Caused By Animal Waste Biological monitoring: Iowa DNR fish kill follow-up New data: recovery of fish community from pollutant-caused fish kill
Documentation
Assessment Summary

The Class BWW2 use was assessed as “not supported” based on biological sampling data. Biological sampling data collected in 2020 showed recovery of the fish community in this segment from the fish kills. Based on the 2020 fish sampling data, the two 5b fish kill impairments were de-listed. Furthermore, the Class BWW2 was assessed as "fully supported" based on continuous dissolved oxygen monitoring 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

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

5bt

Assessment was evaluated because the samples used to complete the

Overall

Evaluated

Fail

Not

assessment were collected in a single year.


Class BWW2 – Fishkill Assessment:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/ Thermal

Fish per mile

REMAP 25 % fish per mile

>REMAP 25 % fish per mile?

2000 305b fish taxa present

Fish Taxa Present %

364

8/17/20

260.6

47a

MO/WW

939.84

524.1

Yes (Pass)

8/9

89% (Pass)

355

8/18/20

43.9

47a

MO/WW

1362.24

524.1

Yes (Pass)

7/9

78% (Pass)

The Class BWW2 use previously resided in Category 5b (two impairments) based on 2002, 2003, 2007 and 2018 fish kills. This segment’s fish community was sampled in 2020 (twice) as part of the DNR fish kill follow-up sampling program. The results from this follow-up sampling and comparison to ecoregion averages suggest that the fish community of this segment is similar to non-fish kill impacted streams. Based on the fish kill follow-up sampling results, the Category for the fish kill assessment was changed from 5b to 3a (not assessed).


Class BWW2- Continuous DO Monitoring:

Site ID

Data Source ID

# Days Monitoring (2016/2017/2018/ 2019/2020)

DO Criteria Type

# 2016 violations / Violations needed for impairment

# 2017 violations / Violations needed for impairment

# 2018 violations / Violations needed for impairment

# 2019 violations / Violations needed for impairment

# 2020 violations / Violations needed for impairment

Violates Annual Significantly >10% Rule?

Assessment Type

Support Level

24 hr

NA

NA

NA

NA

0/5

No

355

6

0/0/0/0/21

16 hr

NA

NA

NA

NA

0/5

No

Monitored

Full

24 hr

NA

NA

NA

NA

0/5

No

364

6

0/0/0/0/19

16 hr

NA

NA

NA

NA

0/5

No

Monitored

Full

Monitoring and Methods
Assessment Key Dates
8/18/2020
Biological Monitoring
8/17/2020
Biological Monitoring
1/8/2002
Fish Kill
9/5/2002
Fish Kill
9/12/2003
Fish Kill
8/4/2007
Fish Kill
8/18/2018
Fish Kill
Methods
120
Surveys of fish and game biologists/other professionals
140
Incidence of spills and/or fish kills
222
Non-fixed-station monitoring (conventional during key seasons and flows)
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys
380
Quantitative physical habitat assessment