Missouri River IA 06-WEM-1709

from water supply intake at Council Bluffs (River Mile 619 in SE 1/4 S22 T75N R44W Pottawattamie Co.) to confluence with Boyer R. in Pottawattamie 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 2018 - 2020
Stream/River Water Quality Data	CY 2018 - 2020
Lake Water Quality Data	CY 2016 - 2020
Biological Sampling Data	CY 2016 - 2020*
Fish Kill Data	CY 2016 - 2020
Fish Tissue Sampling Data	CY 2016 - 2020
Continuous Dissolved Oxygen Sampling Data	CY 2016 - 2020
*Biological sites sampled in both 2015 and 2019 were also assessed.

Open Segment Map
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Cycle: 2022
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 1/6/2022 9:35:51 AM
Updated: 1/6/2022 9:51:51 AM

Use Support

Class A1

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2016

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: USGS

TMDL Priority

Tier III

Class BWW1

Aquatic Life - Warm Water Type 1

Not Supported

Habitat Alterations: Channel Modifications

Support Level

Not Supported

Impairment Code

4c - Non-pollutant caused impairment. No TMDL needed.

Cause Magnitude

Moderate

Status

Continuing

Source

Hydromodification: Flow Regulation/Modification

Source Confidence

N/A

Cycle Added

2002

Impairment Rationale

Adverse impacts on plant/animal communities

Data Source

Ambient monitoring: adjacent state

Class C

Drinking Water -

Fully Supported

Class HH

Human Health -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use remains assessed as “not supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW1 use remains assessed as "not supported" based on information from local fisheries biologists on impacts related to navigation-related flow modifications and habitat alterations in this segment of the Missouri River. The Class C use remains assessed as “fully supported” based on water quality monitoring data. All other designated uses were "not assessed."

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
USGS	11	WQ	CY 2018-2020	6610505	Missouri River near Council Bluffs, IA	Site located in Segment 1708

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

6610505

21/20/10

634

184

388

YES

15 / 5

8 / 5

7 / 3

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
6610505	11	53 / 3	8	8.5	8.2	0	9	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
6610505	11	Ammonia	38 / 3	0.005	0.14	0.04	NA	0 / 0	7	NO	Monitored	Full
6610505	11	Dissolved Oxygen	49 / 3	6.2	13.6	9.6	0	NA / NA	9	NO	Monitored	Full
6610505	11	pH	53 / 3	8	8.5	8.2	0	NA / NA	9	NO	Monitored	Full
6610505	11	Temperature	48 / 3	0	27.7	14.6	0	NA / NA	9	NO	Monitored	Full

Class BWW1 – Historical Assessment:

The Class BWW1 use remains assessed as "not supported" (IR Category 4c, non-pollutant stressor) based on the assessment developed for the 1998, 2000, and 2002 reports (i.e., habitat alterations and flow modifications that resulted from development of the river for navigation uses in the mid-Twentieth Century). The assessment was developed in consultation with the Nebraska Missouri River fisheries biologist.

Class C - 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

6610505

Inorganic nitrogen (nitrate and nitrite)

38 / 3

0.20

2.73

1.46

0 / 0

Monitored

Full

Class HH – No Data

Monitoring and Methods

Assessment Key Dates

1/24/2018

Fixed Monitoring Start Date

12/14/2020

Fixed Monitoring End Date

Methods

120

Surveys of fish and game biologists/other professionals

210

Fixed station physical/chemical monitoring (conventional pollutants only)

420

Indicator bacteria monitoring