2020 Final assessment for Dousman Creek

Dousman Creek IA 01-YEL-438

mouth (S33 T96N R3W Allamakee Co.) to Allamakee-Clayton county line.

Assessment Cycle

2020

Release Status

Final

Data Collection Period

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 2016 - 2018
Stream/River Water Quality Data	CY 2016 - 2018
Lake Water Quality Data	CY 2014 - 2018
Biological Sampling Data	CY 2014 - 2018*
Fish Kill Data	CY 2014 - 2018
Fish Tissue Sampling Data	CY 2014 - 2018
Continuous Dissolved Oxygen Sampling Data	CY 2014 - 2018
*Biological sites sampled in both 2013 and 2017 were also assessed.

Overall IR Category: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown

Created: 8/27/2020 2:42:49 PM
Updated: 10/16/2020 7:06:37 AM

Assessment conducted in accordance with Iowa's 2020 IR methodology

Use Support

Class A1

Presumptive Use

Partially Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Partially Supported

Impairment Code

4a - Pollutant-caused impairment. TMDL has been completed.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

Class A2

Presumptive Use

Not Assessed

Class BCW1

Partially Supported

Organic Enrichment: Low Dissolved Oxygen

Support Level

Partially Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2008

Impairment Rationale

Significantly > 10% of samples fail to meet criterion

Data Source

Watershed project monitoring

TMDL Priority

Tier IV

Class HH

Not Assessed

General Use

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use remains assessed as “partially supported” due to levels of indicator bacteria that exceeded state water quality criteria. The Class BCW1 use remains assessed as "partially supported" based on levels of dissolved oxygen that violated state water quality criteria. All other designated uses were "not assessed". Note: A TMDL for the bacterial impairment for Yellow River basin streams was prepared by DNR in 2012 and was approved by U.S. EPA in February 2013. Due to TMDL completion, the Integrated Report category for the Class A1 recreational use was changed from 5p to 4a.

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY2004-2006, CY2006-2008	15030004	Dousman Creek	YRWP
Iowa DNR	6	BIO	See Below	352	Dousman Creek	Ion

Presumptive Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2006 Geometric Mean	2007 Geometric Mean	2008 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
15030004	6	34 / 3	246	148	322	Yes	15	44%	Yes	Evaluated	Partial

Presumptive Class A2 – No Data

Class BCW1 - Dissolved Oxygen: 2004-2006

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
15030004	6	Dissolved Oxygen	73/ 3	NA	NA	NA	20 / 0	27% / 0%	Yes	Evaluated	Partial

Class BCW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	BM Sample Gear	CBI score	CBI Class	CBI BIT	CBI Pass/ Fail
352	8/12/15	7	52b	MS/CW	Hess	66	NA	60	Pass

Overall Assessment:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (1/1)	Full	1	1	Assessment is evaluated because it was based on a single sample.

Class BCW1 – Trout Natural Reproduction:

Based on the January 2020 trout reproduction in Iowa streams summary prepared by the DNR Fisheries Bureau, the Class BCW1 coldwater aquatic life use of Dousman Creek was assessed as "fully supported". According to the updated summary, this stream was placed in Category I: streams that exhibit consistent natural reproduction and maintain a wild population of one or more trout species without any stocking.

Class HH - No Data

Monitoring and Methods

Assessment Key Dates

1/1/2020	Biological Monitoring
5/20/2004	Non-fixed Monitoring Start Date
11/16/2006	Non-fixed Monitoring End Date
2/1/2006	Non-fixed Monitoring Start Date
9/30/2008	Non-fixed Monitoring End Date
8/12/2015	Biological Monitoring
2/1/2013	TMDL Completed

Methods

120	Surveys of fish and game biologists/other professionals
150	Monitoring data more than 5 years old
220	Non-fixed station physical/chemical monitoring (conventional pollutant only)
315	Regional reference site approach
320	Benthic macroinvertebrate surveys
330	Fish surveys
420	Indicator bacteria monitoring

Water Quality Assessments

Impaired Waters List

Dousman Creek IA 01-YEL-438

Assessment Summary

Assessment Explanation

Assessment Key Dates

Methods