Maquoketa River IA 01-MAQ-19

upper end of Quaker Mill Pond to Forestville Dam at Backbone Lake (SE 1/4 S15 T90N R6W Delaware Co.).

This is a DRAFT assessment

Draft assessments may change without notice

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 2022 - 2024
Stream/River Water Quality Data	CY 2022 - 2024
Lake Water Quality Data	CY 2020 - 2024
Biological Sampling Data	CY 2020 - 2024*
Fish Kill Data	CY 2020 - 2024
Fish Tissue Sampling Data	CY 2020 - 2024
Continuous Dissolved Oxygen Sampling Data	CY 2020 - 2024
*Biological sites sampled in both 2019 and 2023 were also assessed.

Open Segment Map
View 2026 assessment summary page

Cycle: 2026
Current Phase: Public Comment
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Improving
Trend Comment: Monitoring data from 2012-2014 suggested a significant (order of magnitude) decline in levels of indicator bacteria compared to levels in the mid-2000s.
Created: 10/27/2025 3:09:36 PM
Updated: 1/9/2026 10:32:22 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

2010

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Special project/study

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 Class A1 use remains “not supported” due to historic water quality data that showed levels of indicator bacteria (E.coli) slightly exceeded state water quality criteria. The 2023-2024 indicator bacteria data suggested full support for the Class A1 use. However, it was an evaluated assessment due to the number of samples and violations and a monitored assessment is needed to delist the indicator bacteria impairment. The Class BWW1 use was assessed as “fully 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	WQ	CY 2023-2024	15280001	Maquoketa below Backbone
Iowa DNR	6	WQ	CY 2012-2013	15280002	Maquoketa River	Mid Maquoketa
Iowa DNR	6	BIO	See Below	1014	Maquoketa River	N of Manchester - MQ006
Iowa DNR	6	BIO	See Below	1039	Maquoketa River	N of Manchester - MQ004

Class A1 - Indicator Bacteria: Historical

Site ID	Data Source ID	# Samples / # Years	2012 Geometric Mean	2013 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
15280002	6	14 / 2	123	154	Yes	2	14%	No	EVALUATED	Not

Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples per Year (2023/2024)	2023 Geometric Mean	2024 Geometric Mean	Violates Annual Geometric Mean?	# 2022 SSM violations / SSM Violations needed for impairment	# 2023 SSM violations / SSM Violations needed for impairment	# 2024 SSM violations / SSM Violations needed for impairment	Violates Annual SSM Significantly >10% Rule?	Assessment Type	Support Level
15280001	6	8/8	29	75	NO	NA	1 / 3	2 / 3	NO	EVALUATED	FULL

Class BWW1 - Biological Sampling:

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47c FIBI BIT	FIBI Pass/Fail
1014	7/28/22	153	47c	MS	Undetermined	73	Excellent	44/65	Pass
1039	7/27/22	153	47c	MS	Undetermined	80	Excellent	44/65	Pass
1014	7/27/21	153	47c	MS	Undetermined	75	Excellent	44/65	Pass
1039	7/26/21	153	47c	MS	Undetermined	70	Good	44/65	Pass
1014	8/4/20	153	47c	MS	Undetermined	79	Excellent	44/65	Pass
1039	7/31/20	153	47c	MS	Undetermined	78	Excellent	44/65	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Fish	Monitored	Pass (6/6)	Full		Assessment was monitored because multiple samples
Overall	Monitored	Pass	Full	1	collected in the last five years were used for the assessment.

Class HH – No Data

Monitoring and Methods

Assessment Key Dates

5/9/2023

Monitoring Start

9/24/2024

Monitoring End

7/27/2022

Biological Monitoring

7/28/2022

Biological Monitoring

8/4/2020

Biological Monitoring

7/31/2020

Biological Monitoring

7/27/2021

Biological Monitoring

7/26/2021

Biological Monitoring

5/7/2012

Monitoring Start

10/29/2013

Monitoring End

Methods

150

Monitoring data more than 5 years old

315

Regional reference site approach

330

Fish surveys

420

Indicator bacteria monitoring