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

2020

Release Status

Final

Data Collection Period

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.

Overall IR Category: 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend: Stable

Created: 9/18/2020 3:23:02 PM
Updated: 10/19/2020 8:55:46 AM

Assessment conducted in accordance with Iowa's 2020 IR methodology

Use Support

Class A1

Recreation

Primary contact

Partially Supported

Impairments

Support Level

Partially 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

Partially Supported

Impairments

Support Level

Partially Supported

Impairment Code

4a - Pollutant-caused impairment. TMDL has been completed.

Cause Magnitude

Moderate

Status

Continuing

Source

Agriculture

Source Confidence

Moderate

Cycle Added

2010

Impairment Rationale

Significantly > 10% of samples fail to meet criterion

Data Source

Ambient monitoring: municipal water supply

Class HH

Human Health

Fully Supported

General Use

General Use water

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use was assessed as "partially 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 remains assessed as "partially supported" due to high levels of nitrate. 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. Additionally, a TMDL for nitrate was prepared by DNR and approved by EPA in September 2009. Because these TMDL's cover the bacteria and the nitrate impairments identified for this waterbody, the Class A1 and Class C designated uses remain in IR Category 4a (impaired; TMDL approved) for this cycle.

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	BioNet Site ID	Site Name	Site Description
DMWW	13	WQ	CY 2016-2018	99990015		Des Moines River	Des Moines River near the Second Avenue Bridge

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
99990015	13	509 / 3	64.62	51.3	47.89	No	91	18%	Yes	Monitored	Partial

Class A1 - pH:

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
99990015	13	758 / 3	9.37	8.24	8.26	1	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
99990015	13	Chloride	757 / 3	109.03	25.5	24.75	0 / 0	0% / 0%	No	Monitored	Full
99990015	13	pH	758 / 3	9.37	8.24	8.26	1 / NA	0% / NA	No	Monitored	Full
99990015	13	Sulfate	755 / 3	121.52	57.94	53.57	0 / NA	0% / NA	No	Monitored	Full
99990015	13	Temperature	751 / 3	28.3	12.6	12.8	0 / 0	0% / 0%	No	Monitored	Full

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
99990015	13	Chloride	758 / 3	109.03	25.49	24.74	0	0%	No	Monitored	Full
99990015	13	Fluoride	1 / 1	140	140	140	0	0%	No	Evaluated	Full
99990015	13	Inorganic nitrogen (nitrate and nitrite)	759 / 3	15.13	6.91	6.71	143	19%	Yes	Monitored	Partial

Class HH - Fish Tissue Sampling: Fish contaminant monitoring at ISU/ACOE station 5 (17770001) at Sycamore Access in 2014-2016.

The fish consumption (HH) use was assessed as “fully supported” based on results of water quality and fish contaminant monitoring at ISU/ACOE station 5 (17770001) at Sycamore Access in 2014-2016. None of the four samples analyzed for copper contained levels that exceeded the Class HH (human health-fish) criteria. Fish contaminant monitoring conducted downstream from Saylorville Reservoir by ISU/ACOE in 2014, 2015 and 2016 showed low levels of pesticide contaminants (dieldrin, chlordane, trifluralin, and chlorpyrifos) in composite samples of whole fish of common carp. None of the concentrations for chlordane approached Iowa’s thresholds for issuing a one meal per week consumption advisory. Composite samples of whole-fish common carp were analyzed for PCBs in 2016. Levels of PCBs in samples of whole-fish common carp were below levels of detection in 2016. In addition to these pesticide parameters, fillets from smallmouth bass were analyzed for mercury in in 2014 and fillets from largemouth bass were analyzed for mercury in in 2015 and 2016. The results showed that the level of mercury in the 2014 sample from smallmouth bass (0.69 ppm)was above the Hg level of concern (0.3 ppm); however the samples from the 2015 largemouth bass (0.13 ppm) and the 2016 largemouth bass (0.11 ppm) were both below the level of concern.

Monitoring and Methods

Assessment Key Dates

1/4/2016

Fixed Monitoring Start Date

12/31/2018

Fixed Monitoring End Date

5/29/2014

Fish Tissue Monitoring

6/1/2015

Fish Tissue Monitoring

6/1/2016

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