Iowa DNR
ADBNet

Water Quality Assessments

Impaired Waters List

North Raccoon River IA 04-RAC-1132

from confluence with Indian Cr. (S24 T87N R36W Sac Co.) to confluence with Cedar Cr. in S25 T88N R36W Sac Co.

Assessment Cycle
2022
Release Status
Final
Data Collection Period
Overall IR Category
4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend
Unknown
Created
12/27/2021 10:38:46 AM
Updated
1/5/2022 2:21:17 PM
Assessment conducted in accordance with Iowa's 2022 IR methodology
Use Support
Class A1
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
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
Class BWW1
Fully Supported
Class HH
Fully Supported
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class A1 use was assessed as "not supported" due to levels of indicator bacteria (E. coli) that violated state water quality standards. 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 was assessed as "fully supported" based on fish tissue sampling data. Note: A TMDL for pathogen indicator impairments in the Raccoon River basin was approved by EPA in 2008. Because this TMDL covers the primary Section 303(d) impairment identified for the 2006 IR cycle, this segment was moved from IR Category 5a to IR Category 4a (impaired; TMDL approved) for the 2008 cycle. This waterbody remains in IR Category 4a for the current cycle.

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

10810001

North Raccoon River near Sac City (DS1)

Iowa DNR

6

BIO

See Below

222

North Raccoon River

Sac City

Iowa DNR

6

FT

See Below

82

North Raccoon River

Downstream of Sac City

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

10810001

6

8/6/8

488

310

227

YES

4 / 3

3 / NA

4 / 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

10810001

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

10810001

6

Ammonia

36 / 3

0.025

1.3

0.1

NA

0 / 0

7

NO

Monitored

Full

10810001

6

Chloride

36 / 3

9.6

63

24.6

NA

0 / 0

7

NO

Monitored

Full

10810001

6

Dissolved Oxygen

36 / 3

7.3

14.9

10.3

0

NA / NA

7

NO

Monitored

Full

10810001

6

pH

36 / 3

7.1

8.6

8.1

0

NA / NA

7

NO

Monitored

Full

10810001

6

Sulfate

36 / 3

15

140

50

0

NA / NA

7

NO

Monitored

Full

10810001

6

Temperature

36 / 3

0

27.3

11.1

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

10810001

6

Aluminum

14 / 3

3

0.821

0.835

0 / 0

NO

Monitored

Full

10810001

6

Arsenic

13 / 3

4

2.3

2.2

0 / 0

NO

Monitored

Full

10810001

6

Cadmium

13 / 3

0.05

0.03

0.02

0 / 0

NO

Monitored

Full

10810001

6

Chromium

13 / 3

1.3

0.7

0.8

0 / 0

NO

Monitored

Full

10810001

6

Lead

13 / 3

0.2

0.1

0.1

0 / 0

NO

Monitored

Full

10810001

6

Nickel

13 / 3

4.4

3.3

3.2

0 / 0

NO

Monitored

Full

10810001

6

Silver

13 / 3

0.025

0.025

0.025

0 / 0

NO

Monitored

Full

10810001

6

Zinc

13 / 3

5.7

2.6

2.1

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

47b BMIBI BIT

BMIBI Pass/Fail

222

8/20/19

709

47b

MS

Floating Art Sub

56

Good

62

Fail

222

8/11/16

709

47b

MS

Floating Art Sub

63

Good

62

Pass

222

7/27/15

709

47b

MS

Floating Art Sub

69

Good

62

Pass

Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Pass (2/3)

Full

Assessment was evaluated because the drainage area of the site is

Overall

Evaluated

Pass

Full

1

greater than the calibrated range.


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)

82

fillet

2012

channel catfish

3

44

0.147

0.03

0.09

82

tissue plug

2016

walleye

3

53.6

0.25

Support Level

Full

Monitoring and Methods
Assessment Key Dates
7/27/2015 Biological Monitoring
1/10/2018 Fixed Monitoring Start Date
12/3/2020 Fixed Monitoring End Date
8/11/2016 Biological Monitoring
8/25/2016 Fish Tissue Monitoring
8/20/2019 Biological Monitoring
6/24/2008 TMDL Completed
7/1/2012 Fish Tissue Monitoring
Methods
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