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 2016 - 2018
Stream/River Water Quality Data	CY 2016 - 2018
Lake Water Quality Data	CY 2014 - 2018
Biological Sampling Data	CY 2014 - 2018*
Fish Kill Data	CY 2014 - 2018
Fish Tissue Sampling Data	CY 2014 - 2018
Continuous Dissolved Oxygen Sampling Data	CY 2014 - 2018
*Biological sites sampled in both 2013 and 2017 were also assessed.

Open Segment Map
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Cycle: 2020
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 10/8/2020 9:17:49 AM
Updated: 10/16/2020 12:55:28 PM

Use Support

Class A1

Recreation - Primary contact

Partially Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Partially 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

Partially Supported

Habitat Alterations: Channel Modifications

Support Level

Partially 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

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use remains assessed as “partially supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW1 aquatic life use remains assessed as "partially 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 2016-2018	06610505	Missouri River near Council Bluffs	Site located in Segment 1708

Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2016 Geometric Mean	2017 Geometric Mean	2018 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
06610505	11	59 / 3	323.5	613.71	634.42	Yes	39	66%	Yes	Monitored	Partial

Class A - pH:

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
06610505	11	81 / 3	8.5	8.2	8.2	0	0%	No	Monitored	Full

Class BWW1 - Conventional Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Acute / Chronic Violations	% Acute/ Chronic Violations	Significantly >10% Violations	Assessment Type	Support Level
06610505	11	Ammonia	40 / 3	0.27	0.05	0.03	0 / 0	0% / 0%	No	Monitored	Full
06610505	11	Dissolved oxygen	81 / 3	13.6	9.7	9.1	NA / 0	NA / 0%	No	Monitored	Full
06610505	11	pH	81 / 3	8.5	8.2	8.2	0 / NA	0% / NA	No	Monitored	Full
06610505	11	Temperature	81 / 3	28.7	14.5	14.3	0 / 0	0% / 0%	No	Monitored	Full

Class BWW1 – Additional Information:

The Class BWW1 aquatic life use remains assessed as "partially supported" (IR Category 4c, non-pollutant stressor) based on the assessment developed for previous reporting cycles (i.e., habitat alterations and flow modifications that resulted from development of the river for navigation uses in the mid-Twentieth Century). This assessment was developed in consultation with the Missouri River fisheries biologist for the state of Nebraska.

Class C - Conventional Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
06610505	11	Inorganic nitrogen (nitrate and nitrite)	40 / 3	5.42	2.3	2.2	0	0%	No	Monitored	Full

Class HH – No Data:

Monitoring and Methods

Assessment Key Dates

1/20/2016

Fixed Monitoring Start Date

12/20/2018

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