Des Moines River IA 04-UDM-1212

from the Interstate 80/35 bridge (S17 T79N R24W Polk Co.) to Saylorville Dam in S30 T80N R24W Polk 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.

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Cycle: 2022
Release Status: Final
Overall IR: 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
Trend: Stable
Created: 12/28/2021 5:25:17 AM
Updated: 1/13/2022 1:16:10 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Fully Supported

Class BWW1

Aquatic Life - Warm Water Type 1

WINOFI

Biological: low aquatic macroinvertebrate IBI

Support Level

Further Investigation Needed

Impairment Code

3b-u - Use potentially biologically impaired based on uncalibrated IBI metrics.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2014

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

Class C

Drinking Water -

Fully Supported

Class HH

Human Health -

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as "fully supported" based on indicator bacteria monitoring. The Class BWW1 use was assessed as "WINOFI” based on biological sampling data. The Class C (drinking water) use was assessed as "fully supported" based on 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 the nitrate impairment in this segment was approved by EPA in September 2009. The TMDL covered the nitrate impairment identified for this segment and the impairment remained in IR Category 4a (impaired; TMDL approved) until this cycle. 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
USACE	12	WQ	CY 2018-2020	17770001	Des Moines River at 66th. St.	Site 5
Iowa DNR	6	BIO	See Below	917	Des Moines River	Des Moines – US1
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

17770001

10/10/10

0 / 3

1 / 3

Monitored

Full

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
17770001	12	60 / 3	6.06	9.01	8.01	2	10	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
17770001	12	Ammonia	60 / 3	0.02	1.49	0.21	NA	0 / 2	10	NO	Monitored	Full
17770001	12	Dissolved Oxygen	60 / 3	7.75	15.36	11.35	0	NA / NA	10	NO	Monitored	Full
17770001	12	pH	60 / 3	6.06	9.01	8.01	2	NA / NA	10	NO	Monitored	Full
17770001	12	Temperature	60 / 3	0.2	29.1	14.5	0	NA / NA	10	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
17770001	12	Lead	5 / 3	0.2	0.1	0.05	0 / 0	NO	Evaluated	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
17770001	12	Inorganic nitrogen (nitrate and nitrite)	60 / 3	0.2	9.2	4.5	5.3	0	NO	Monitored	Full
17770001	12	pH	60 / 3	6.06	9.01	8.01	8.07	2	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
917	9/17/14	5840	47b	MS	Floating Art Sub	29	Poor	62	Fail

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/1)	Not		Assessment was evaluated because the drainage area of the site
Overall	Evaluated	Fail	WINOFI	3bu	was 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)
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

9/17/2014

Biological Monitoring

12/7/2020

Fixed Monitoring End Date

1/8/2018

Fixed Monitoring Start Date

6/1/2016

Fish Tissue Monitoring

9/1/2009

TMDL Completed

Methods

150

Monitoring data more than 5 years old

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