Rock Creek IA 02-CED-493

mouth (S2 T79N R3W Cedar Co.) to confluence with unnamed tributary in SW 1/4 S11 T80N R3W Cedar 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 2020 - 2022
Stream/River Water Quality Data	CY 2020 - 2022
Lake Water Quality Data	CY 2018 - 2022
Biological Sampling Data	CY 2018 - 2022*
Fish Kill Data	CY 2018 - 2022
Fish Tissue Sampling Data	CY 2018 - 2022
Continuous Dissolved Oxygen Sampling Data	CY 2018 - 2022
*Biological sites sampled in both 2017 and 2021 were also assessed.

Open Segment Map
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Cycle: 2024
Release Status: Final
Overall IR: 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
Trend: Unknown
Created: 11/1/2023 8:12:39 AM
Updated: 1/12/2024 1:42:38 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW1

Aquatic Life - Warm Water Type 1

Fully Supported

Class HH

Human Health -

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class BWW1 use was assessed as "fully supported" based on biological sampling data. The Class HH use remains assessed as "fully supported" based on fish tissue sampling data. All other designated uses were "not assessed."

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	BIO	See Below	27	Rock Creek	Tipton
Iowa DNR	6	FT	See Below	1354	Rock Creek	Tipton

Presumptive Class A1 – No Data

Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	47f BMIBI BIT	BMIBI Pass/Fail
27	9/24/20	55.2	47f	MS	Hess	73	Good	51	Pass
27	9/7/16	55.2	47f	MS	Hess	65	Good	51	Pass

Fish:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47f FIBI BIT	FIBI Pass/Fail
27	9/24/20	55.2	47f	MS	NA	71	Excellent	36	Pass
27	9/7/16	55.2	47f	MS	NA	72	Excellent	36	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (2/2)	Full
Fish	Evaluated	Pass (2/2)	Full		Assessment was evaluated because the assessment used
Overall	Evaluated	Pass	Full	1	samples not collected in a recent five-year period.

Class HH - Fish Tissue Sampling:

Site ID	Biopart	Year	Species	# in sample / # of samples	Avg Length (cm)	(Avg) Hg (ppm)	Chlordane (ppm)	Sum PCBs (ppm)
1354	tissue plug	2016	smallmouth bass	3	34.7	0.203
Support Level	Full

Monitoring and Methods

Assessment Key Dates

9/7/2016

Biological Monitoring

9/7/2016

Fish Tissue Monitoring

9/24/2020

Biological Monitoring

Methods

150

Monitoring data more than 5 years old

260

Fish tissue analysis

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys