Ten Mile Creek IA 01-UIA-274

mouth (S1 T98N R9W Winneshiek Co.) to confluence with Walnut Cr. in S18 T98N R9W Winneshiek Co.

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: 8/24/2020 3:23:34 PM
Updated: 10/15/2020 11:37:39 AM

Assessment conducted in accordance with Iowa's 2020 IR methodology

Use Support

Class A1

Recreation

Primary contact

Presumptive Use

Partially Supported

Impairments

Support Level

Partially Supported

Impairment Code

5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.

Cause Magnitude

Slight

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 A2

Recreation

Secondary contact

Presumptive Use

Fully Supported

Class BCW1

Aquatic Life

Cold Water Type 1

Partially Supported

Impairments

Support Level

Partially Supported

Impairment Code

5b-v - Biological - verified

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2008

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

TMDL Priority

Tier IV

Class HH

Human Health

Not Assessed

General Use

General Use water

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use remains assessed as “partially supported” based on levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The presumptive Class A2 use remains assessed as “fully supported” based on indicator bacteria (E. coli) monitoring data. The Class BCW1 use remains assessed as "partially supported" based on biological sampling data. All other designated uses were "not assessed".

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	BIO	See Below	476	Ten Mile Creek	Decorah – REMAP #169
Iowa DNR	6	BIO	See Below	829	Ten Mile Creek	Ridgeway
NEIARCD	19	WQ	CY2012-2014	191910006	Ten Mile Creek	Site 26

Presumptive Class A1 - Indicator Bacteria:

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
191910006	19	21 / 3	110	315	506	Yes	12	57%	Yes	Evaluated	Partial

Presumptive Class A2 - Indicator Bacteria:

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
191910006	19	21 / 3	110	315	506	No	3	14%	No	Evaluated	Full

Class A - pH:

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
191910006	19	13 / 3	10.93	8.65	8.37	2	15%	No	Evaluated	Full

Class BCW1 - Conventional Parameters:

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
191910006	19	Ammonia	14 / 3	0.18	0.06	0.05	0 / 0	0% / 0%	No	Evaluated	Full
191910006	19	pH	13 / 3	10.93	8.65	8.37	2 / 0	15% / 0%	No	Evaluated	Full
191910006	19	Temperature	14 / 3	21.1	14.7	16.4	NA / 0	NA / 0%	No	Evaluated	Full

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
476	8/12/14	29	52b	MS/CW	Hess	56	NA	60	Fail
476	8/7/13	13	52b	MS/CW	Hess	66	NA	60	Pass
829	8/16/11	29	52b	MS/CW	Hess	50	NA	60	Fail

Overall Assessment:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (1/3)	Partial	3bc	5bv	Assessment is evaluated because samples used to complete assessment weren’t collected in the last five years.

Class HH - No Data

Monitoring and Methods

Assessment Key Dates

4/3/2012

Non-fixed Monitoring Start Date

10/7/2014

Non-fixed Monitoring End Date

8/16/2011

Biological Monitoring

8/7/2013

Biological Monitoring

8/12/2014

Biological Monitoring

Methods

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

420

Indicator bacteria monitoring