West Branch Floyd River IA 06-FLO-1558

from confluence with Orange City Slough (S28 T94N R45W Sioux Co.) to confluence with unnamed tributary in NE 1/4 S18 T96N R44W Sioux Co.

Open Data Collection Period Modal

For purposes of developing stream/river water quality assessments for integrated reporting, three years of water quality data are typically used for both conventional pollutant parameters (e.g., indicator bacteria) and the less frequently monitored toxic parameters (e.g., toxic metals). Since the 2004 IR cycle, DNR has used a three-year data gathering period for streams, rivers, and beaches. For most assessments, the use of three years of data increases the number of samples upon which the decision on use support is based and helps address the problem of weather-related year-to-year fluctuations in water quality.

Due to the lower sampling frequency in Iowa’s ambient lake, biological, fish kill, and fish tissue monitoring programs, five years of data are used for developing IR assessments and for identifying Section 303(d) listings.

Data Type	Data Timeframe
Beach Sampling Data	CY 2020 - 2022
Stream/River Water Quality Data	CY 2020 - 2022
Lake Water Quality Data	CY 2018 - 2022
Biological Sampling Data	CY 2018 - 2022*
Fish Kill Data	CY 2018 - 2022
Fish Tissue Sampling Data	CY 2018 - 2022
Continuous Dissolved Oxygen Sampling Data	CY 2018 - 2022
*Biological sites sampled in both 2017 and 2021 were also assessed.

Open Segment Map
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Cycle: 2024
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 12/8/2023 1:18:55 PM
Updated: 2/2/2024 10:47:26 AM

Use Support

Class A3

Recreation - Children's contact

Not Assessed

Class BWW2

Aquatic Life - Warm Water Type 2

Not Supported

Biological: low fish IBI

Support Level

Not 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

Impairment Delistings

Cycle Added	Class	Cause	Data Source	Rationale
2018	Class BWW2	Fish Kill: Cause Unknown	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. 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	256	West Branch Floyd River	Hull
Iowa DNR	6	BIO	See Below	1394	West Branch Floyd River	Sioux Center (FKF)

Class A3 - No Data

Class BWW2 - Biological Sampling:

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	Riffle Stream?	FIBI score	FIBI Class	47a FIBI BIT	FIBI Pass/Fail
256	9/13/01	62	47a	MO/WW	NA	22	Poor	43	Fail

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Fish	Evaluated	Fail (0/1)	Not
Overall	Evaluated	Fail	Not	5bt	Assessment was evaluated because it was based on a single sample.

Class BWW2 – Fish kill Assessment:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	Fish per mile	47a REMAP 25 % fish per mile	>47a REMAP 25 % fish per mile?	2024 IR 47a expected fish taxa	Fish Taxa Present % (>50% to pass)
1394	10/10/22	111.0	47a	MO/WW	6135	496	Yes (Pass)	7/10	70% (Pass)
The Class BWW2 use previously resided in Category 5b based on 2007, 2012, and 2016 fish kills. This segment’s fish community was sampled in 2022 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).

Details about the 2016 fish kill can be found here: https://programs.iowadnr.gov/fishkill/Events/954

Monitoring and Methods

Assessment Key Dates

9/13/2001

Biological Monitoring

8/10/2016

Fish Kill

10/10/2022

Biological Monitoring

Methods

150

Monitoring data more than 5 years old

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys