Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Des Moines River IA 04-LDM-1012

from confluence with Cedar Cr. (S33 T75N R17W Mahaska Co.) to dam of Red Rock Reservoir in S19 T76N R18W Marion Co.

Assessment Cycle
2024
Release Status
Final
Data Collection Period
Overall IR Category
1 - All designated uses are met.
Trend
Unknown
Created
11/1/2023 8:13:15 AM
Updated
1/10/2024 8:01:09 AM
Assessment conducted in accordance with Iowa's 2024 IR methodology
Use Support
Class A1
Recreation
Primary contact
Fully Supported
Class BWW1
Aquatic Life
Warm Water Type 1
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 "fully supported" based on the results of routine monitoring for indicator bacteria (E. coli). The Class BWW1 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.

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

USACE

12

WQ

CY 2020-2022

17630001

Des Moines River at Howell Station Landing

USACE

12

FT

See Below

17630001

Des Moines River at Howell Station Landing

Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2020/ 2021/2022)

2020 Geometric Mean

2021 Geometric Mean

2022 Geometric Mean

Violates Annual Geometric Mean?

# 2020 SSM violations / SSM Violations needed for impairment

# 2021 SSM violations / SSM Violations needed for impairment

# 2022 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

17630001

12

10/10/10

14

15

14

NO

0 / 3

1 / 3

1 / 3

NO

Mon

Full

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

17630001

12

60 / 3

6.79

8.96

8.25

0

10

NO

Mon

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

17630001

12

Dissolved Oxygen

60 / 3

6.29

17.04

11.03

0

NA / NA

10

NO

Mon

Full

17630001

12

pH

60 / 3

6.79

8.96

8.25

0

NA / NA

10

NO

Mon

Full

17630001

12

Temperature

60 / 3

1.6

29.1

16.2

0

NA / NA

10

NO

Mon

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

17630001

12

Ammonia

19 / 1

0.01

0.01

0

0 / 0

NO

Mon

Full

Class HH - Fish Tissue Sampling: 2012-2014 at site 17630001

Fish contaminant monitoring showed low levels of contaminants (dieldrin, heptachlor epoxide, chlordane, alachlor, and trifuluralin) in composite samples of whole fish common carp. Levels of PCBs in composite whole-fish carp samples for all Aroclors analyzed in from 2012 to 2014 (1016, 1221, 1232, 1242, 1248, 1254, and 1260) were all below levels of detection. Detection levels for PCB were high in all three years; thus, data for PCBs are inconclusive. The history of low levels of PCBs in fish from this river segment, however, suggest that PCB levels are below the one meal per week advisory trigger of 0.20 ppm for total PCBs (sum of Aroclors 1248, 1254, and 1260).

Composite samples of fillets from a predator species were analyzed for mercury in all three years. In 2012, the composite sample of largemouth bass fillets had low levels of mercury (0.14 mg/kg). The average levels of mercury in the composite sample of smallmouth bass fillets in 2013 was 0.10 ppm. Results were not reported for levels of mercury in the 2014 composite sample of predator fish. Levels of mercury in the samples from this river segment from 2012 and 2013 were below the one meal per week advisory threshold for mercury (0.30 ppm). Based on this information, fish consumption uses are assessed (evaluated) as "fully supported."

Monitoring and Methods
Assessment Key Dates
5/23/2012
Fish Tissue Monitoring
8/8/2013
Fish Tissue Monitoring
1/6/2020
Monitoring Start
12/5/2022
Monitoring End
Methods
200
Physical/Chemical Monitoring
260
Fish tissue analysis
420
Indicator bacteria monitoring