Cedar River IA 02-CED-457

from confluence with Bear Cr. (NE 1/4 S21 T84N R8W Linn Co.) to confluence with Hinkle Cr. in SW 1/4 S16 T85N R10W Benton Co.

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: 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
Trend: Unknown
Created: 8/28/2020 12:20:11 PM
Updated: 10/12/2020 1:57:43 PM

Use Support

Class A1

Recreation - Primary contact

Fully Supported

Class BWW1

Aquatic Life - Warm Water Type 1

WINOFI

Biological: low aquatic macroinvertebrate IBI

Support Level

Further Investigation Needed

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

2014

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

Class HH

Human Health -

Not Assessed

General Use

General Use water -

Not Assessed

Impairment Delistings

Cycle Added	Class	Cause	Data Source	Rationale
2014	Class A1	pH	Ambient monitoring: Iowa DNR-rivers	New data: WQ improvement (chemical / physical / bacterial)
2014	Class BWW1	pH	Ambient monitoring: Iowa DNR-rivers	New data: WQ improvement (chemical / physical / bacterial)

Documentation

Assessment Summary

The Class A1 primary contact recreation use was assessed as “fully supported” based on 2016-2018 pH monitoring data. Since this was the second consecutive cycle that pH data did not violate the pH criteria, the Class A1 pH impairment has been de-listed. The Class BWW1 aquatic life use was assessed as "partially supported" based on 2011 biological sampling data. Additionally, since this was the second consecutive cycle that pH data did not violate the pH criteria, the Class BWW1 aquatic life pH impairment has been de-listed. 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
USGS	11	WQ	CY 2016-2018	5464420	Cedar River at Blairs Ferry Road at Palo, IA	Site is located outside this segment and will no longer be used for assessing this segment.
Iowa DNR	6	BIO	See Below	869	Cedar River	Palo (dstr of DAEC)

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
5464420	11	27 / 3	8.9	8.1	8.1	0	0%	No	Monitored	Full

Class BWW1 – pH Monitoring:

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
5464420	11	pH	27 / 3	8.9	8.1	8.1	0 / NA	0% / NA	No	Monitored	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
869	10/7/11	6238	47c	MS/WW	Hess	45	Fair	70	Fail

Overall Assessment:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/1)	Partial	3bu	3bu	Assessment is evaluated because the drainage area of the sample site is larger than calibrated range.

Monitoring and Methods

Assessment Key Dates

10/7/2011

Biological Monitoring

1/5/2016

Fixed Monitoring Start Date

12/26/2018

Fixed Monitoring End Date

Methods

150

Monitoring data more than 5 years old

230

Fixed station physical/chemical (conventional plus toxic pollutants)

315

Regional reference site approach

320

Benthic macroinvertebrate surveys