2020 assessment for Cedar Creek

Cedar Creek IA 03-SKU-6549

from Lake Geode (T70N R5W Sec25 Henry Co.) to headwaters (T70N R4W Sec5 Des Moines Co.)

2020
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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Overall IR

5 - Water is impaired or threatened and a TMDL is needed.

Trend

Unknown

Created

9/23/2020 9:27:45 AM by

Updated

10/9/2020 1:14:53 PM by

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.

Cause Magnitude

High

303(d) Listing Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2014

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Special project/study

TMDL Priority

Tier III

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

Not Assessed

General Use

General Use water -

Not Assessed

303(d) Delistings for this Cycle

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as “not supported” due to violations of Iowa water quality criteria for indicator bacteria (E. coli). 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 2016-2017	13290001	Cedar Creek near US Hwy 34 (Site A)
Iowa DNR	6	WQ	CY 2016-2017	13290002	Cedar Creek at 135th St (Site B)
Iowa DNR	6	WQ	CY 2016-2017	13290003	Cedar Creek at 130th St (Site C)
Iowa DNR	6	WQ	CY 2016-2017	13290006	Cedar Creek at Roosevelt St (Site F)
Iowa DNR	6	WQ	CY 2016-2017	13440001	Cedar Creek near Danville

Presumptive 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
13290001	6	9 / 2	813.57	342.9	NA	Yes	6	67%	Yes	Evaluated	Partial
13290002	6	10 / 2	956.69	2066.82	NA	Yes	8	80%	Yes	Evaluated	Not
13290003	6	10 / 2	5485.31	1098.48	NA	Yes	9	90%	Yes	Evaluated	Not
13290006	6	10 / 2	1649.12	1620.82	NA	Yes	8	80%	Yes	Evaluated	Not
13440001	6	35 / 2	476.27	217.85	NA	Yes	25	71%	Yes	Monitored	Partial

Presumptive Class BWW1 - No Data

Monitoring and Methods

Assessment Key Dates

9/22/2017

Non-fixed Monitoring End Date

3/16/2016

Non-fixed Monitoring Start Date

Methods

220

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

420

Indicator bacteria monitoring