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

2022

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 2018 - 2020
Stream/River Water Quality Data	CY 2018 - 2020
Lake Water Quality Data	CY 2016 - 2020
Biological Sampling Data	CY 2016 - 2020*
Fish Kill Data	CY 2016 - 2020
Fish Tissue Sampling Data	CY 2016 - 2020
Continuous Dissolved Oxygen Sampling Data	CY 2016 - 2020
*Biological sites sampled in both 2015 and 2019 were also assessed.

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

Created: 12/22/2021 6:56:48 AM
Updated: 3/30/2022 9:32:29 AM

Assessment conducted in accordance with Iowa's 2022 IR methodology

Use Support

Class A1

Recreation

Primary contact

Not Supported

Impairments

Support Level

Not 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

Fully Supported

Class HH

Human Health

Not Supported

Impairments

Support Level

Not 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

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use was assessed as "not supported" due to violations of Class A1 criteria for indicator bacteria (E. coli). The Class BWW1 use was assessed as "fully supported" based on biological sampling data and water quality monitoring data. The Class HH (fish consumption) use remains assessed as "not supported" based on fish tissue sampling data. Note: A TMDL for the bacteria impairment in the Cedar River was prepared and was approved by EPA in February 2010. However, this segment was not included in the TMDL; therefore, the bacteria impairment of the Class A1 primary contact recreation use for this segment remains in IR Category 5a (TMDL needed).

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2018-2020	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 per Year (2018/ 2019/2020)

2018 Geometric Mean

2019 Geometric Mean

2020 Geometric Mean

Violates Annual Geometric Mean?

# 2018 SSM violations / SSM Violations needed for impairment

# 2019 SSM violations / SSM Violations needed for impairment

# 2020 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

10340001

7/8/8

153

151

YES

3 / 3

0 / 3

YES

Monitored

Not

Class A - pH:

Site ID	Data Source ID	# Samples / # Years	Minimum Value	Maximum Value	Mean Value	# Violations	Violations needed for impairment	Violates Significantly >10% Rule?	Assessment Type	Support Level
10340001	6	36 / 3	7.1	8.6	8.1	0	7	NO	Monitored	Full

Class BWW1 - Conventional Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Minimum Value	Maximum Value	Mean Value	# Violations	# Acute / Chronic Violations	Violations needed for impairment	Violates Significantly >10% Rule?	Assessment Type	Support Level
10340001	6	Ammonia	36 / 3	0.025	0.9	0.1	NA	0 / 0	7	NO	Monitored	Full
10340001	6	Chloride	36 / 3	8.8	36	21.5	NA	0 / 0	7	NO	Monitored	Full
10340001	6	Dissolved Oxygen	36 / 3	7.3	14.8	10.7	0	NA / NA	7	NO	Monitored	Full
10340001	6	pH	36 / 3	7.1	8.6	8.1	0	NA / NA	7	NO	Monitored	Full
10340001	6	Sulfate	36 / 3	8.1	32	21.2	0	NA / NA	7	NO	Monitored	Full
10340001	6	Temperature	36 / 3	0.1	26.4	10.7	0	NA / NA	7	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	>1 Acute / Chronic Violation	Assessment Type	Support Level
10340001	6	Aluminum	14 / 3	2.2	0.4	0.1	0 / 0	NO	Monitored	Full
10340001	6	Arsenic	13 / 3	10	5.21	6.1	0 / 0	NO	Monitored	Full
10340001	6	Cadmium	13 / 3	0.08	0.03	0.02	0 / 0	NO	Monitored	Full
10340001	6	Chromium	13 / 3	1.2	0.9	0.9	0 / 0	NO	Monitored	Full
10340001	6	Lead	13 / 3	0.18	0.11	0.1	0 / 0	NO	Monitored	Full
10340001	6	Nickel	13 / 3	3.5	2.7	2.7	0 / 0	NO	Monitored	Full
10340001	6	Silver	13 / 3	0.025	0.025	0.025	0 / 0	NO	Monitored	Full
10340001	6	Zinc	13 / 3	3.3	1.9	1.8	0 / 0	NO	Monitored	Full

Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	47c BMIBI BIT	BMIBI Pass/ Fail
285	8/9/20	1095	47c	MS	Floating Art Sub	76	Excellent	52	Pass
285	8/15/16	1095	47c	MS	Hess	86	Excellent	70	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (2/2)	Full		Assessment was evaluated because the drainage area of the sample site
Overall	Evaluated	Pass	Full	1	was greater than the calibrated range.

Class BWW1 - Continuous DO Monitoring:

Site ID	Data Source ID	# Days Monitoring (2016/2017/2018/ 2019/2020)	DO Criteria Type	# 2016 violations / Violations needed for impairment	# 2017 violations / Violations needed for impairment	# 2018 violations / Violations needed for impairment	# 2019 violations / Violations needed for impairment	# 2020 violations / Violations needed for impairment	Violates Annual Significantly >10% Rule?	Assessment Type	Support Level
			24 hr	0/5	NA	NA	NA	NA	No
285	6	24/0/0/0/0	16 hr	0/5	NA	NA	NA	NA	No	Evaluated	Full

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)
61	fillet	2012	channel catfish	5	40.6	0.172	0.03	0.09
61	tissue plug	2014	smallmouth bass	4	35.1	0.27
61	tissue plug	2012	smallmouth bass	5	37.9	0.464
Support Level	Not	A one meal/week mercury consumption advisory for any predator fish exists on this segment. Based on IR Methodology, the Class HH (fish consumption) use was assessed as “not supported.”

Monitoring and Methods

Assessment Key Dates

9/22/2014

Fish Tissue Monitoring

8/15/2016

Biological Monitoring

1/8/2018

Fixed Monitoring Start Date

12/7/2020

Fixed Monitoring End Date

8/9/2020

Biological Monitoring

9/12/2012

Fish Tissue Monitoring

Methods

150

Monitoring data more than 5 years old

222

Non-fixed-station monitoring (conventional during key seasons and flows)

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