Des Moines River IA 04-LDM-1003

from confluence with Sugar Cr. (S25 T65N R6W Lee Co.) to confluence with Indian Cr. in S35 T68N R8W Van Buren 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: 8/12/2020 10:22:02 AM
Updated: 10/16/2020 11:40:26 AM

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

2008

Impairment Rationale

Single-sample maximum criterion exceeded in significantly > 10% of samples

Data Source

Ambient monitoring: Iowa DNR-rivers

TMDL Priority

Tier III

Class BWW1

Aquatic Life - Warm Water Type 1

Not Assessed

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 remains assessed as "partially supported” due to levels of indicator bacteria (E. coli) that exceeded state criteria. The Class HH use remains assessed as "fully supported" based on turtle tissue sampling. All other designated uses were "not assessed".

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2004-2006	10560001	Des Moines River	Highway 61 bridge south of Keokuk
Iowa DNR	6	FT	See Below	189	Des Moines River	Near Croton

Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2004-2006 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
10560001	6	24 / 3	79	No	6	25%	Yes	Evaluated	Partial

Class BWW1 - No Data

Class HH – Fish Tissue Sampling:

Site ID	Date	Species	Chlordane Result	Chlordane Violation (>0.6)?	Mercury Result	Mercury Violation (>0.3)?	PCBs Result	PCBs Violation (>0.2)?	Assessment Type	Support Level
189	8/29/13	Softshell Turtle	<0.2	No	0.09	No	<0.6*	No	Evaluated	Full
*In 2013, the lab reported non-detected Total PCB results as <0.6 ppm which higher than Iowa’s one meal/week advisory level.

Monitoring and Methods

Assessment Key Dates

1/20/2004

Non-fixed Monitoring Start Date

11/2/2006

Non-fixed Monitoring End Date

8/29/2013

Fish Tissue Monitoring

Methods

150

Monitoring data more than 5 years old

220

Non-fixed station physical/chemical monitoring (conventional pollutant only)

260

Fish tissue analysis

420

Indicator bacteria monitoring