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
2020
Release Status
Final
Overall IR
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
6/19/2020 9:31:05 AM
Updated
10/15/2020 11:35:55 AM
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class BWW2
Aquatic Life - Warm Water Type 2
Partially Supported
Support Level
Partially Supported
Impairment Code
5b - Biological impairment or pollutant-caused fish kill - unknown source. No administrative action.
Cause Magnitude
High
Status
Continuing
Source
Agriculture: Intensive Animal Feeding Operations
Source Confidence
Moderate
Cycle Added
2004
Impairment Rationale
Pollutant-caused fish kill
Data Source
Fish kill investigation: Iowa DNR
TMDL Priority
Tier IV
Support Level
Partially Supported
Impairment Code
5b - Biological impairment or pollutant-caused fish kill - unknown source. No administrative action.
Cause Magnitude
High
Status
Continuing
Source
Agriculture: Agricultural chemical dealer
Source Confidence
Moderate
Cycle Added
2004
Impairment Rationale
Pollutant-caused fish kill
Data Source
Fish kill investigation: Iowa DNR
TMDL Priority
Tier IV
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
General Use water -
Not Assessed
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class BWW2 use remains assessed as “partially supported” based on reoccurring fish kills in this segment and on the results of 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

355

Floyd River

Sanborn – REMAP #67

Iowa DNR

6

BIO

See Below

364

Floyd River

Alton – REMAP #85

Iowa DNR

6

BIO

See Below

617

Floyd River

Hospers – REMAP #225

Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/ Thermal

BM Sample Gear

BMIBI score

BMIBI Class

47a BMIBI BIT

BMIBI Pass/ Fail

617

8/16/06

234

47a

MO/WW

ArtSub

50

Fair

54

Fail

364

8/6/03

261

47a

MO/WW

ArtSub

65

Good

54

Pass

Fish:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/ Thermal

Riffle Stream?

FIBI score

FIBI Class

47a FIBI BIT

FIBI Pass/ Fail

617

8/16/06

234

47a

MO/WW

NA

22

Poor

43

Fail

364

8/7/03

261

47a

MO/WW

NA

18

Poor

43

Fail

355

7/30/03

44

47a

MO/WW

NA

37

Fair

43

Fail

Overall:

Community

Assessment Type

Assessment Result

Support Level

Earned IR Category

Actual IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (1/2)

Partial

Fish

Evaluated

Fail (0/3)

Partial

Overall

Evaluated

Fail

Partial

3bc

5bt

Assessment is evaluated because it was based on samples not collected in the last five years.

Class BWW2 – Fish kill Assessment:

The Class BWW2 aquatic life use assessment based on the reoccurring fish kills resulted in two Category 5b impairments because there were two distinct causes. The fish kills were caused by a “pollutant” or were suspected to be caused by a “pollutant”; therefore, the Class BWW2 use was considered impaired. Because the sources of the pollutants were not identified and/or the enforcement actions taken against the responsible party have not been resolved, the presumptive Class BWW2use was placed in Category 5b. Due to uncertainty regarding the recovery of the aquatic life following the fish kill, any existing fish kill 5b impairment will remain in Category 5b until more recent sampling has shown recovery of the aquatic community or the responsible party has paid restitution.

More details about the 2018 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/988

More details about the 2007 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/731

More details about the 2003 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/579

More details about the September 2002 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/529

More details about the January 2002 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/503

Monitoring and Methods
Assessment Key Dates
7/30/2003
Biological Monitoring
8/7/2003
Biological Monitoring
8/16/2006
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
150
Monitoring data more than 5 years old
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys