Cedar River IA 02-CED-477

from upper end of Nashua Impoundment (Chickasaw/Floyd county line (W line S7 T94N R14W Chickasaw Co.)) to Dam No. 2 at Charles City in NW 1/4 NE 1/4 S12 T95N R16W Floyd 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: 8/28/2020 1:47:23 PM
Updated: 10/26/2020 10:17:58 AM

Assessment conducted in accordance with Iowa's 2020 IR methodology

Use Support

Class A1

Recreation

Primary contact

Partially Supported

Impairments

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

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: Iowa DNR-rivers

TMDL Priority

Tier III

Class BWW1

Aquatic Life

Warm Water Type 1

WINOFI

Further Investigation Needed

Support Level

Water in Need of Further Investigation (WINOFI)

Impairment Code

3b-u - Use potentially biologically impaired based on uncalibrated IBI metrics.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2004

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

Class HH

Human Health

Partially Supported

Impairments

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

2014

Impairment Rationale

Potential fish consumption advisory; additional sampling needed

Data Source

Fish contaminant monitoring: Iowa DNR

TMDL Priority

Tier IV

General Use

General Use water

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use was assessed as "partially supported" due to violations of Class A1 criteria for indicator bacteria (E. coli). The Class BWW1 use was assessed as "partially supported" based on biological sampling data. The Class HH use remains assessed as "partially supported" based on fish tissue sampling data.

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2016-2018	10340001	Cedar River near Charles City (DS1)
Iowa DNR	6	BIO	See Below	285	Cedar River	Carrville/Charles City
Iowa DNR	6	FT	See Below	61	Cedar River	At Midway

Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2016 Geometric Mean	2017 Geometric Mean	2018 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
10340001	6	20 / 3	165.63	57.47	153.09	Yes	7	35%	Yes	Monitored	Partial

Class A1 - pH:

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
10340001	6	36 / 3	8.7	8.2	8.3	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
10340001	6	Ammonia	36 / 3	1.9	0.12	0.02	0 / 0	0% / 0%	No	Monitored	Full
10340001	6	Chloride	36 / 3	36	23	24	0 / 0	0% / 0%	No	Monitored	Full
10340001	6	Dissolved oxygen	36 / 3	15.2	11.2	11.4	NA / 0	NA / 0%	No	Monitored	Full
10340001	6	pH	36 / 3	8.7	8.2	8.3	0 / NA	0% / NA	No	Monitored	Full
10340001	6	Sulfate	36 / 3	32	22.3	21	0 / NA	0% / NA	No	Monitored	Full
10340001	6	Temperature	36 / 3	25.6	11.2	10.2	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
10340001	6	Aluminum	9 / 2	1.1	0.412	0.22	0 / 0	0% / 0%	No	Evaluated	Full
10340001	6	Arsenic	9 / 2	10	5.6	6.1	0 / 0	0% / 0%	No	Evaluated	Full
10340001	6	Cadmium	9 / 2	0.025	0.025	0.025	0 / 0	0% / 0%	No	Evaluated	Full
10340001	6	Chromium	9 / 2	1.2	0.85	0.85	0 / 0	0% / 0%	No	Evaluated	Full
10340001	6	Copper	9 / 2	3	1.11	0.83	0 / 0	0% / 0%	No	Evaluated	Full
10340001	6	Lead	9 / 2	0.16	0.064	0.07	0 / 0	0% / 0%	No	Evaluated	Full
10340001	6	Nickel	9 / 2	3.3	2.5	2.3	0 / 0	0% / 0%	No	Evaluated	Full
10340001	6	Selenium	9 / 2	2.2	1.53	1.5	0 / 0	0% / 0%	No	Evaluated	Full
10340001	6	Zinc	9 / 2	2.9	1.65	1.6	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
285	8/15/16	1095	47c	MS/WW	Hess	86	Excellent	70	Pass
285	9/8/14	1095	47c	MS/WW	Float ArtSub	27	Poor	52	Fail
285	9/4/13	1095	47c	MS/WW	ArtSub	50	Fair	52	Fail

Overall Assessment:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (1/3)	Partial	3bu	3bu	Assessment is evaluated because it used a site with a drainage area larger than the calibrated range.

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

9/22/14

smallmouth bass

plug

0.270

Monitored

Full

9/12/12

smallmouth bass

plug

0.464

Yes

Evaluated

Partial

9/12/12

channel catfish

fillet

<0.03

0.09

0.172

Evaluated

Full

Although the 2014 fish tissue sampling result was “fully supported”, de-listing a Category 5a mercury impairment requires two sample results less than the 0.3 ppm advisory threshold. Additional fish tissue sampling is recommended for this segment.

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
10340001	6	Cadmium	9 / 2	0.025	0.025	0.025	9	No	All Non-Detect	Full
10340001	6	Chromium	9 / 2	1.2	0.85	0.85	0	No	Evaluated	Full
10340001	6	Copper	9 / 2	3	1.11	0.83	0	No	Evaluated	Full
10340001	6	Nickel	9 / 2	3.3	2.5	2.3	0	No	Evaluated	Full
10340001	6	Selenium	9 / 2	2.2	1.53	1.5	0	No	Evaluated	Full
10340001	6	Zinc	9 / 2	2.9	1.65	1.6	0	No	Evaluated	Full

Monitoring and Methods

Assessment Key Dates

9/22/2014

Fish Tissue Monitoring

8/15/2016

Biological Monitoring

1/7/2016

Fixed Monitoring Start Date

12/11/2018

Fixed Monitoring End Date

8/7/2012

Biological Monitoring

9/4/2013

Biological Monitoring

9/8/2014

Biological Monitoring

9/12/2012

Fish Tissue Monitoring

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