DRAFT 2026 assessment for Tetes Des Morts Creek

Tetes Des Morts Creek IA 01-TRK-121

mouth (Dubuque Co.) to confluence with Lux Cr. in S7 T87N R4E Jackson Co.

This is a DRAFT assessment

Draft assessments may change without notice

2026
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

Overall IR

5 - Water is impaired or threatened and a TMDL is needed.

Trend

Stable

Current Phase

Public Comment

Created

10/27/2025 3:09:01 PM by

Updated

1/9/2026 10:53:32 AM by

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

High

303(d) Listing Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2012

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

TMDL Priority

Tier III

Class BWW1

Aquatic Life - Warm Water Type 1

Fully Supported

Class HH

Human Health -

Fully Supported

303(d) Delistings for this Cycle

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use remains assessed as “not supported” due to violations of Iowa water quality criteria for indicator bacteria (E. coli). The Class BWW1 use was assessed as "fully supported" based on biological sampling data. The Class HH use remains assessed as "fully supported" based on fish tissue sampling data.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2024-2024	13490002	Tete des Morts at High Bridge Road (Site 3)
Iowa DNR	6	BIO	See Below	231	Tetes des Morts Creek	At St Donatus (original bio site)
Iowa DNR	6	FT	See Below	1355	Tetes des Morts Creek	At St Donatus

Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples per Year (2024)	2024 Geometric Mean	Violates Annual Geometric Mean?	# 2024 SSM violations / SSM Violations needed for impairment	Violates Annual SSM Significantly >10% Rule?	Assessment Type	Support Level
13490002	6	10	1327	YES	10 / 3	YES	MONITORED	NOT

BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/ Thermal	BM Sample Gear	BMIBI score	BMIBI Class	52b BMIBI BIT	BMIBI Pass/Fail
231	7/20/20	40	52b	MS/WW	Hess	64	Good	61	Pass
231	8/16/19	40	52b	MS/WW	Hess	71	Good	61	Pass

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/ Thermal	Riffle Stream?	FIBI score	FIBI Class	52b FIBI BIT	FIBI Pass/ Fail
231	9/25/17	40	52b	MS/WW	NA	69	Good	52	Pass
231	9/14/16	40	52b	MS/WW	NA	67	Good	52	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Monitored	Pass (2/2)	Full
Fish	Evaluated	Pass (2/2)	Full		Assessment was monitored because the benthic macroinvertebrate
Overall	Monitored	Pass	Full	1	assessment used multiple samples collected in a recent five year period.

Class HH - Fish Tissue Sampling:

Site ID	Biopart	Year	Species	# in sample / # of samples	Avg Length (cm)	(Avg) Hg (ppm)	Chlordane (ppm)	Sum PCBs (ppm)
1355	tissue plug	2016	smallmouth bass	3	32	0.143
Support Level	Full

Monitoring and Methods

Assessment Key Dates

4/16/2024

Monitoring Start

11/14/2024

Monitoring End

8/16/2019

Biological Monitoring

9/14/2016

Biological Monitoring

9/14/2016

Fish Tissue Monitoring

9/25/2017

Biological Monitoring

7/20/2020

Biological Monitoring

Methods

150

Monitoring data more than 5 years old

260

Fish tissue analysis

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

420

Indicator bacteria monitoring