Shell Rock River IA 02-SHL-787

from confluence with Rose Cr. (NW 1/4 S8 T97N R19W Cerro Gordo Co.) to the Iowa/Minnesota state line.

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 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.

Open Segment Map
View assessment methodology in new window

Cycle: 2020
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 9/8/2020 7:59:18 AM
Updated: 10/12/2020 2:22:42 PM

Use Support

Class A1

Recreation - Primary contact

Partially Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Partially 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

Ambient monitoring: adjacent state

TMDL Priority

Tier III

Class BWW1

Aquatic Life - Warm Water Type 1

WINOFI

Biological: low fish & invert IBIs- cause unknown

Support Level

Further Investigation Needed

Impairment Code

3b-c - Use potentially biologically impaired based on calibrated IBI metrics.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2006

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

Class HH

Human Health -

Fully Supported

General Use

General Use water -

Not Assessed

Impairment Delistings

Cycle Added	Class	Cause	Data Source	Rationale
2020	Class BWW1	Organic Enrichment: Low Dissolved Oxygen	Ambient monitoring: adjacent state	New data: WQ improvement (chemical / physical / bacterial)

Documentation

Assessment Summary

The Class A1 primary contact recreation use remains assessed as “partially supported” based on the 2006 results of monitoring for indicator bacteria. The Class BWW1 aquatic life use was assessed as “partially supported” based on 2002 biological sampling data. The Class HH (fish consumption) use was assessed as "fully supported" based on 2015 fish tissue data and 2016-2018 water quality monitoring data. Note: This is the second consecutive cycle that the dissolved oxygen data met the dissolved oxygen criteria; therefore, the Class BWW1 dissolved oxygen impairment was "de-listed". Monitoring for indicator bacteria has not been conducted at this station since 2010. Although recreation season geometric means for 2009 and 2010 were very low and easily met the Class A1 geometric mean criterion, the Class A1 uses of this segment remain assessed as "partially supported" based on results of ambient monitoring for indicator bacteria (E. coli) in 2006. According to DNR’s assessment/listing methodology, indicator bacteria must meet the criteria for two consecutive cycles to be "de-listed".

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
MNPCA	15	WQ	CY 2006, 2009-2010, 2016-2018	99990013	Shellrock River	MPCA station S000-084 near Gordonsville, MN
Iowa DNR	6	BIO	See Below	331	Shellrock River	Kensett – REMAP #23
Iowa DNR	6	FT	See Below	110	Shellrock River	S of Northwood

Class A1 - Indicator Bacteria: 2006-2008

Site ID	Data Source ID	# Samples / # Years	2006 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
99990013	15	12 / 1	198	Yes	6	50%	Yes	Evaluated	Partial

Class A1 - Indicator Bacteria: 2009-2010

Site ID	Data Source ID	# Samples / # Years	2009 Geometric Mean	2010 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
99990013	15	15 / 2	78	84	No	2	13%	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
99990013	15	45 / 3	8.62	8.07	8.05	0	0%	No	Monitored	Full

Class BWW1 - 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
99990013	15	Dissolved oxygen	46 / 3	16.05	10.64	10.8	NA / 0	NA / 0%	No	Monitored	Full
99990013	15	pH	45 / 3	8.62	8.07	8.05	0 / NA	0% / NA	No	Monitored	Full
99990013	15	Temperature	46 / 3	26.2	13.32	14.03	0 / 0	0% / 0%	No	Monitored	Full

Class BWW1 - Toxic Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Acute / Chronic Violations	% Acute/ Chronic Violations	>1 Acute / Chronic Violation	Assessment Type	Support Level
99990013	15	Mercury	3 / 1	0.00297	0.0019	0.0018	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
331	10/15/02	306	47c	MS/WW	Hess	57	Good	70	Fail

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	Riffle Stream?	FIBI score	FIBI Class	47c FIBI BIT	FIBI Pass/ Fail
331	10/16/02	306	47c	MS/WW	Yes	7	Poor	65	Fail

Overall:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/1)	Partial
Fish	Evaluated	Fail (0/1)	Not
Overall	Evaluated	Fail	Partial	3bc	3bc	Assessment is evaluated because it was based on an old single sample.

Class HH-F - Toxic Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	Number of Non - Detects	Mean Value > Criterion or MCL	Assessment Type	Support Level
99990013	15	Mercury	3 / 1	0.00297	0.0019	0.0018	0	No	Evaluated	Full

Class HH – Fish Tissue Sampling:

Site ID

Date

Species Name

Biopart

# in sample

chlordane result

chlordane violation (>0.6)?

PCBs result

PCBs violation (>0.2)?

Hg result

Hg violation (>0.3)?

Assessment Type

Support Level

110

8/25/2015

common carp

fillet

<0.02

<0.06

0.19

Monitored

Full

110

8/14/2015

walleye

plug

0.218

Monitored

Full

Monitoring and Methods

Assessment Key Dates

10/16/2002

Biological Monitoring

8/14/2015

Fish Tissue Monitoring

1/21/2009

Fixed Monitoring Start Date

2/28/2016

Fixed Monitoring Start Date

11/26/2018

Fixed Monitoring End Date

8/25/2015

Fish Tissue Monitoring

2/14/2006

Fixed Monitoring Start Date

10/30/2008

Fixed Monitoring End Date

11/15/2010

Fixed Monitoring End Date

Methods

150

Monitoring data more than 5 years old

230

Fixed station physical/chemical (conventional plus toxic pollutants)

260

Fish tissue analysis

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

420

Indicator bacteria monitoring