Winnebago River IA 02-WIN-827

from confluence with Calmus Cr. (S34 T97N R20W Cerro Gordo Co.) to mill dam at Fertile in S34 T98N R22W Worth 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: 11/1/2023 8:12:51 AM
Updated: 1/16/2024 8:47:24 AM

Use Support

Class A1

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: Iowa DNR-rivers

TMDL Priority

Tier III

Class BWW1

Aquatic Life - Warm Water Type 1

Fully Supported

Class HH

Human Health -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as "not supported" due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW1 use was assessed as "fully supported" based on biological sampling data and on ambient water quality 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	WQ	CY 2012-2014	10170002	Winnebago River Upstream of Mason City (US1)
Iowa DNR	6	BIO	See Below	953	Winnebago River	Mason City – US1

Presumptive Class A1 - Indicator Bacteria: 2012-2014

Site ID	Data Source ID	# Samples / # Years	2012 Geometric Mean	2013 Geometric Mean	2014 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
10170002	6	21 / 3	279	87	170	Yes	7	33%	Yes	Evaluated	Not

Presumptive Class A1 - pH: 2012-2014

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
10170002	6	33 / 3	8.5	8.1	8.1	0	0%	No	Evaluated	Full

Class BWW1 - Binomial Parameters: 2012-2014

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Acute / Chronic Violations	% Acute/ Chronic Violations	Significantly >10% Violations	Assessment Type	Support Level
10170002	6	Ammonia	33 / 3	0.72	0.11	0.05	0 / 0	0% / 0%	No	Evaluated	Full
10170002	6	Chloride	33 / 3	120	27	24	0 / 0	0% / 0%	No	Evaluated	Full
10170002	6	Dissolved oxygen	33 / 3	15.7	10.2	9.9	NA / 0	NA / 0%	No	Evaluated	Full
10170002	6	pH	33 / 3	8.5	8.1	8.1	0 / NA	0% / NA	No	Evaluated	Full
10170002	6	Sulfate	33 / 3	130	68	70	0 / NA	0% / NA	No	Evaluated	Full
10170002	6	Temperature	33 / 3	28.3	11.7	14.5	0 / 0	0% / 0%	No	Evaluated	Full

Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	BM Sample Gear	BMIBI score	BMIBI Class	47c BMIBI BIT	BMIBI Pass/Fail
953	9/8/14	463	47c	MS/WW	Hess	80	Excellent	70	Pass
953	9/8/14	463	47c	MS/WW	Float ArtSub	80	Excellent	52	Pass
953	9/4/13	463	47c	MS/WW	Hess	73	Good	70	Pass
953	9/4/13	463	47c	MS/WW	ArtSub	77	Excellent	52	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (4/4)	Full	1	Assessment was evaluated because it included samples collected not in the last five years.

Overall Assessment:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (4/4)	Full		Assessment was evaluated because it included samples
Overall	Evaluated	Pass	Full	1	not collected in a recent five-year period.

Class HH - No Data

Monitoring and Methods

Assessment Key Dates

9/4/2013

Biological Monitoring

9/8/2014

Biological Monitoring

1/3/2012

Monitoring Start

9/8/2014

Monitoring End

Methods

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

420

Indicator bacteria monitoring