Cedar River IA 02-CED-456

from confluence with McCloud Run (SW 1/4 S16 T83N R7W Linn Co.) to confluence with Bear Cr. in NE 1/4 S21 T84N R8W Linn Co. (includes East West Seminole and Northwest well fields for city of Cedar Rapids water supply).

This is a DRAFT assessment

Draft assessments may change without notice

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 2022 - 2024
Stream/River Water Quality Data	CY 2022 - 2024
Lake Water Quality Data	CY 2020 - 2024
Biological Sampling Data	CY 2020 - 2024*
Fish Kill Data	CY 2020 - 2024
Fish Tissue Sampling Data	CY 2020 - 2024
Continuous Dissolved Oxygen Sampling Data	CY 2020 - 2024
*Biological sites sampled in both 2019 and 2023 were also assessed.

Open Segment Map
View 2026 assessment summary page

Cycle: 2026
Current Phase: Public Comment
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Stable
Created: 10/27/2025 3:09:58 PM
Updated: 1/9/2026 11:26:52 AM

Use Support

Class A1

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

4a - Pollutant-caused impairment. TMDL has been completed.

Cause Magnitude

Slight

Status

New

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2026

Impairment Rationale

Single-sample maximum criterion exceeded in significantly > 10% of samples

Data Source

Ambient monitoring: municipal water supply

Class BWW1

Aquatic Life - Warm Water Type 1

Not Supported

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

Potential Impairment

Data Source

Biological monitoring: Iowa DNR WQMA

Metals: Copper

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2022

Impairment Rationale

Violations of acute criterion

Data Source

Ambient monitoring: municipal water supply

TMDL Priority

Tier IV

Class C

Drinking Water -

Fully Supported

Class HH

Human Health -

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use was assessed as "not supported" based on violations of indicator bacteria (E. coli) criteria. The Class BWW1 use was assessed as "not supported" based on violations of the acute/chronic copper water quality criteria. The Class C (drinking water) and the Class HH (fish consumption) uses were assessed as "fully supported" based on water quality monitoring data. Note: A TMDL for nitrate in this segment of the Cedar River was prepared by DNR and approved by EPA in January 2007 and a TMDL for E. coli in this segment of the Cedar River was prepared by DNR and approved by EPA in January 2010.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
CRWW	14	WQ	CY 2022-2024	99990021	Cedar River
Iowa DNR	6	WQ	CY 2022-2022	14000348	Cedar River
USGS	11	WQ	CY 2022-2024	5464420	Cedar River at Blairs Ferry Road at Palo, IA
CRWW	14	WQ	CY 2022-2024	99990313	Cedar River
Iowa DNR	6	BIO	See Below	1260	Cedar River	Cedar Rapids-REMAP #410

Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2022/ 2023/2024)

2022 Geometric Mean

2023 Geometric Mean

2024 Geometric Mean

Violates Annual Geometric Mean?

# 2022 SSM violations / SSM Violations needed for impairment

# 2023 SSM violations / SSM Violations needed for impairment

# 2024 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

99990021

36/35/32

4 / 7

1 / 7

7 / 6

YES

MONITORED

NOT

Class A1 - 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
14000348	6	7 / 1	8.03	8.85	8.47	0	3	NO	EVALUATED	FULL
5464420	11	29 / 3	7.7	9	8.2	0	6	NO	MONITORED	FULL
99990021	14	123 / 3	6.93	8.71	7.41	0	18	NO	MONITORED	FULL
99990313	14	30 / 3	6.96	8.25	7.36	0	6	NO	MONITORED	FULL

Class BWW1 - Binomial 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
5464420	11	Chloride	12 / 3	21	42.3	31.4	NA	0 / 0	4	NO	MONITORED	FULL
99990021	14	Chloride	123 / 3	15.2	52.3	31.6	NA	0 / 0	18	NO	MONITORED	FULL
99990313	14	Chloride	30 / 3	22.8	64.9	38.2	NA	0 / 0	6	NO	MONITORED	FULL
14000348	6	Dissolved Oxygen	7 / 1	7.74	15.44	12.5	0	NA / NA	3	NO	EVALUATED	FULL
5464420	11	Dissolved Oxygen	29 / 3	7.5	16.5	12.4	0	NA / NA	6	NO	MONITORED	FULL
14000348	6	pH	7 / 1	8.03	8.85	8.47	0	NA / NA	3	NO	EVALUATED	FULL
5464420	11	pH	29 / 3	7.7	9	8.2	0	NA / NA	6	NO	MONITORED	FULL
99990021	14	pH	123 / 3	6.93	8.71	7.41	0	NA / NA	18	NO	MONITORED	FULL
99990313	14	pH	30 / 3	6.96	8.25	7.36	0	NA / NA	6	NO	MONITORED	FULL
5464420	11	Sulfate	12 / 3	25	43.8	33.8	0	NA / NA	4	NO	MONITORED	FULL
99990021	14	Sulfate	123 / 3	14.5	56.9	31.5	0	NA / NA	18	NO	MONITORED	FULL
99990313	14	Sulfate	30 / 3	17	56.5	37	0	NA / NA	6	NO	MONITORED	FULL
14000348	6	Temperature	7 / 1	6.53	26.34	18.94	0	NA / NA	3	NO	EVALUATED	FULL
5464420	11	Temperature	29 / 3	-0.1	25.9	12.4	0	NA / NA	6	NO	MONITORED	FULL
99990021	14	Temperature	123 / 3	0.4	27.6	16.1	0	NA / NA	18	NO	MONITORED	FULL
99990313	14	Temperature	30 / 3	-0.11111	22	4.213	0	NA / NA	6	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
5464420	11	4,4-DDT	9 / 3	0.00135	0.0014	0.0014	0 / 0	NO	EVALUATED	FULL
99990021	14	Ammonia	122 / 3	0.38	0.05	0.03	0 / 0	NO	MONITORED	FULL
99990313	14	Ammonia	29 / 3	0.36	0.1	0.06	0 / 0	NO	MONITORED	FULL
99990021	14	Copper	123 / 3	95.5	21.1	9.3	39 / 49	YES	MONITORED	NOT
99990313	14	Copper	30 / 3	56.7	11.1	2.2	5 / 7	YES	MONITORED	NOT

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
1260	9/22/20	6450	47c	MS	Floating Art Sub	35	Fair	52	Fail

Fish:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47c FIBI BIT	FIBI Pass/Fail
1260	9/23/20	6450	47c	MS	Undetermined	79	Excellent	44	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/1)	WINOFI
Fish	Evaluated	Pass (1/1)	Full		Assessment was evaluated because the drainage area of
Overall	Evaluated	Fail	WINOFI	3bu	the sample site was greater than the calibrated range.

Class C - Binomial Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Minimum Value	Maximum Value	Mean Value	Median Value	# Violations	Violates Significantly >10% Rule?	Assessment Type	Support Level
5464420	11	Chloride	12 / 3	21	42.3	31.4	31.2	0	NO	MONITORED	FULL
99990021	14	Chloride	123 / 3	15.2	52.3	31.6	31.1	0	NO	MONITORED	FULL
99990313	14	Chloride	30 / 3	22.8	64.9	38.1	36.6	0	NO	MONITORED	FULL
5464420	11	Fluoride	12 / 3	180	220	197	195	0	NO	MONITORED	FULL
99990021	14	Fluoride	123 / 3	150	240	203	200	0	NO	MONITORED	FULL
99990313	14	Fluoride	30 / 3	170	230	207	210	0	NO	MONITORED	FULL
5464420	11	Nitrate	19 / 2	0.1	10.3	4.9	4.5	1	NO	MONITORED	FULL
99990021	14	Nitrate	123 / 3	0.1	18.2	4.9	4	15	NO	MONITORED	FULL
99990313	14	Nitrate	30 / 3	2.4	15.1	5.4	5	2	NO	MONITORED	FULL
5464420	11	Nitrite	27 / 3	0.002	0.173	0.025	0.017	0	NO	MONITORED	FULL
99990021	14	Nitrite	123 / 3	0.005	0.084	0.024	0.021	0	NO	MONITORED	FULL
99990313	14	Nitrite	30 / 3	0.01	0.15	0.04	0.03	0	NO	MONITORED	FULL
14000348	6	pH	7 / 1	8.03	8.85	8.47	8.59	0	NO	EVALUATED	FULL
5464420	11	pH	29 / 3	7.7	9	8.2	8.2	0	NO	MONITORED	FULL
99990021	14	pH	123 / 3	6.93	8.71	7.41	7.29	0	NO	MONITORED	FULL
99990313	14	pH	30 / 3	6.96	8.25	7.36	7.18	0	NO	MONITORED	FULL

Class C - 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
5464420	11	Carbofuran	9 / 3	0.00065	0.0006	0.0006	9	NO	EVALUATED	FULL
Site ID	Data Source ID	Parameter Name	# Samples per Year (2022/ 2023/2024)	2022 Mean	2023 Mean	2024 Mean	# Non-Detects per Year (2022/ 2023/2024)	Support Level per Year (2022/ 2023/2024)	Assessment Type	Support Level
5464420	11	Atrazine	4/4/4	0.091	0.099	0.059	0/0/0	FS/FS/FS	MONITORED	FULL
5464420	11	Simazine	4/4/4	0.007	0.006	0.003	2/1/2	FS/FS/FS	MONITORED	FULL

Class C - Iowa Drinking Water Compliance Report:

Compliance monitoring required by the Iowa DNR Water Supply Operations and Engineering Sections did not show violations of finished water caused by source water at the Cedar Rapids Water Department during the 2022-24 monitoring period. The results of compliance monitoring as reported in annual compliance reports are available at the following location at the Iowa DNR’s home page:https://www.iowadnr.gov/Environmental-Protection/Water-Quality/Water-Supply-Engineering/Annual-Compliance-Report.

Class HH-FW - 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
5464420	11	4,4-DDD	9 / 3	0.00135	0.0014	0.0014	9	NO	EVALUATED	FULL
5464420	11	4,4-DDE	9 / 3	0.0015	0.0015	0.0015	9	NO	EVALUATED	FULL
5464420	11	4,4-DDT	9 / 3	0.00135	0.0014	0.0014	9	NO	EVALUATED	FULL

Monitoring and Methods

Assessment Key Dates

1/4/2022

Monitoring Start

12/17/2024

Monitoring End

9/23/2020

Biological Monitoring

1/24/2007

TMDL Completed

2/26/2010

TMDL Completed

Methods

200

Physical/Chemical Monitoring

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

420

Indicator bacteria monitoring

860

Other Agencies/Organizations provided monitoring data