Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Des Moines River IA 04-UDM-1211

from Center Street Dam in Des Moines to the Interstate 80/35 bridge in S17 T79N R24W Polk 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
Stable
Created
12/30/2021 6:20:41 AM
Updated
12/30/2021 6:30:03 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
4a - Pollutant-caused impairment. TMDL has been completed.
Cause Magnitude
Slight
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2010
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
Fully Supported
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 levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW1 use was assessed as "fully supported" based on water quality monitoring data. The Class C use was assessed as "fully supported" based on water quality monitoring data. The Class HH use was assessed as "fully supported" based on fish tissue sampling data. A TMDL for bacteria was prepared by DNR and approved by U.S. EPA in March 2010. Because this TMDL covers the bacteria impairment identified for this segment, the Class A1 designated use remain in IR Category 4a (impaired; TMDL approved) for this cycle. Additionally, a TMDL for nitrate was prepared by DNR and approved by EPA in September 2009. However, the 2018-2020 nitrate monitoring data indicated "full support."

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

DMWW

13

WQ

CY 2018-2020

99990015

Des Moines River

USACE

12

FT

See Below

17770001

Des Moines River at 66th. St.

Site 5

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

99990015

13

170/170/170

48

39

35

NO

32 / 23

30 / 23

30 / 23

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

99990015

13

760 / 3

7.27

8.86

8.26

0

88

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

99990015

13

Chloride

758 / 3

0.5

83.6

22.9

NA

0 / 0

87

NO

Monitored

Full

99990015

13

pH

760 / 3

7.27

8.86

8.26

0

NA / NA

88

NO

Monitored

Full

99990015

13

Sulfate

758 / 3

4.75

121.52

54.06

0

NA / NA

87

NO

Monitored

Full

99990015

13

Temperature

758 / 3

-1.11

28.33

11.89

0

NA / NA

87

NO

Monitored

Full

Class C - Conventional 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

99990015

13

Chloride

758 / 3

0.5

83.6

22.9

20

0

NO

Monitored

Full

99990015

13

Fluoride

752 / 3

100

520

354

360

0

NO

Monitored

Full

99990015

13

Nitrate

758 / 3

0.02

8.95

4.22

4.66

0

NO

Monitored

Full

99990015

13

pH

760 / 3

7.27

8.86

8.26

8.28

0

NO

Monitored

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)

17770001

whole

2016

common carp

5

NA

NA

0.03

<0.06

17770001

fillet

2016

largemouth bass

2

NA

0.11

Support Level

Full

Monitored

Monitoring and Methods
Assessment Key Dates
1/4/2016
Fixed Monitoring Start Date
12/31/2020
Fixed Monitoring End Date
1/2/2018
Fish Tissue Monitoring
3/1/2010
TMDL Completed
9/1/2009
TMDL Completed
Methods
230
Fixed station physical/chemical (conventional plus toxic pollutants)
260
Fish tissue analysis
270
PWS chemical monitoring (ambient water)
420
Indicator bacteria monitoring