Roberts Creek IA 01-TRK-188

from confluence with Silver Cr. (S16 T94N R5W Clayton Co.) to confluence with unnamed tributary in S8 T95N R6W Clayton 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: 8/21/2020 8:15:20 AM
Updated: 10/15/2020 12:23:03 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

2014

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

TMDL Priority

Tier III

Class BWW2

Aquatic Life - Warm Water Type 2

Fully Supported

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use remains assessed as “not supported” due to violations of Iowa water quality criteria for indicator bacteria (E. coli). The Class BWW2 use was assessed as "fully supported" based on biological sampling data and water quality monitoring data.

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 2012-2014	15220019	Roberts Creek at Dalmatian Ave	Site ROB-50
Iowa DNR	6	BIO	See Below	310	Roberts Creek	Gunder – REMAP #11

Presumptive Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2012 Geometric Mean	2013 Geometric Mean	2014 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
15220019	6	24 / 3	259	1682	234	Yes	19	79%	Yes	Evaluated	Not

Class A - pH:

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
15220019	6	22 / 3	8.8	8.22	8.2	0	0%	No	Evaluated	Full

Class BWW2 - 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
15220019	6	Ammonia	14 / 2	0.56	0.09	0.05	0 / 0	0% / 0%	No	Evaluated	Full
15220019	6	Chloride	16 / 2	33	31	31	NA / 0	NA / 0%	No	Evaluated	Full
15220019	6	Dissolved Oxygen	24 / 3	12	9.4	10	0 / NA	0% / NA	No	Evaluated	Full
15220019	6	pH	22 / 3	8.8	8.22	8.2	0 / 0	0% / 0%	No	Evaluated	Full
15220019	6	Temperature	24 / 3	25.6	15.1	16.6	NA / 0	NA / 0%	No	Evaluated	Full

Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/ Thermal	BM Sample Gear	BMIBI score	BMIBI Class	52b BMIBI BIT	BMIBI Pass/ Fail
310	7/31/17	34	52b	MS/WW	Hess	66	Good	61	Pass
310	8/8/12	34	52b	MS/WW	Hess	49	Fair	61	Fail
310	8/12/09	34	52b	MS/WW	Hess	67	Good	61	Pass

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/ Thermal	Riffle Stream?	FIBI score	FIBI Class	52b FIBI BIT	FIBI Pass/ Fail
310	8/1/17	34	52b	MS/WW	NA	53	Good	52	Pass
310	8/8/12	34	52b	MS/WW	NA	45	Fair	52	Fail
310	8/12/09	34	52b	MS/WW	NA	55	Good	52	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (2/3)	Full
Fish	Evaluated	Pass (2/3)	Full
Overall	Evaluated	Pass	Full	1	1	Assessment is evaluated because samples older than five years were used to complete the assessment.

Monitoring and Methods

Assessment Key Dates

7/31/2017

Biological Monitoring

8/12/2009

Biological Monitoring

8/8/2012

Biological Monitoring

4/4/2012

Non-fixed Monitoring Start Date

11/5/2014

Non-fixed Monitoring End Date

Methods

150

Monitoring data more than 5 years old

220

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

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

420

Indicator bacteria monitoring