Robin Creek IA 01-NEM-6373

from mouth (SW1/4 S14 T78N R3E Scott Co.) to headwaters in SW1/4 S10 T78N R3E Scott 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.

Open Segment Map
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Cycle: 2022
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 1/11/2022 3:36:00 PM
Updated: 1/11/2022 3:37:20 PM

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

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2010

Impairment Rationale

Geometric mean criterion exceeded

Data Source

TMDL monitoring: Iowa DNR

TMDL Priority

Tier III

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as "not supported" due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. All other designated uses were "not assessed." Note: A TMDL for the bacterial impairment for streams in the Duck Creek basin was prepared by Iowa DNR in March 2010 and was approved by U.S. EPA in 2011. According to U.S. EPA, however, the TMDL for the Duck Creek watershed does not assign the required elements to Robin Creek; thus, this stream remains Section 303(d) impaired and in Category 5p of Iowa's Integrated Report.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2008	11820007	Robin Creek site along W 35 St. (RC1A)
Iowa DNR	6	WQ	CY 2013	11820010	Robin Creek (rc1a)

Presumptive Class A1 - Indicator Bacteria: Historical

Site ID	Data Source ID	# Samples / # Years	2008 Geometric Mean	2013 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
11820007	6	29 / 1	1308	NA	Yes	26	90%	Yes	Evaluated	Not
11820010	6	6 / 1	NA	895	Yes	4	67%	Yes	Evaluated	Not

Presumptive Class BWW1 – No Data

Monitoring and Methods

Assessment Key Dates

4/8/2008

Non-fixed Monitoring Start Date

10/28/2008

Non-fixed Monitoring End Date

5/19/2013

Non-fixed Monitoring Start Date

11/20/2013

Non-fixed Monitoring End Date

Methods

150

Monitoring data more than 5 years old

220

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

420

Indicator bacteria monitoring