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 2012 - 2014
Stream/River Water Quality Data	CY 2012 - 2014
Lake Water Quality Data	CY 2010 - 2014
Biological Sampling Data	CY 2010 - 2014*
Fish Kill Data	CY 2010 - 2014
Fish Tissue Sampling Data	CY 2010 - 2014
Continuous Dissolved Oxygen Sampling Data	CY 2010 - 2014
*Biological sites sampled in both 2009 and 2013 were also assessed.

Open Segment Map
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Cycle: 2016
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: 9/15/2016 12:40:51 PM
Updated: 11/30/2016 11:01:55 AM

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 -

Not Assessed

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 (primary contact recreation) uses remain "not assessed" (IR 3a) due to the lack of information upon which to base an assessment. The Class B(WW-1) aquatic life uses remain assessed (evaluated) as "fully supported" (IR 2a) based on results of IDNR/SHL biological sampling in 2001, 2008 and 2012 and Fisheries sampling in 2002. Fish consumption uses remain "not assessed" (IR 3a) due to the lack of fish contaminant monitoring in this stream segment.

Assessment Explanation

The Class B(WW1) aquatic life uses remain assessed (evaluated) as “fully supporting” based on data collected in 2001, 2008 and 2012 as part of the IDNR/SHL stream biocriteria project and on data collected in 2002 as part of a IDNR Fisheries stream sampling project: Manchester research station. The 2012 FIBI score was 65 (good) and the BMIBI score was 50 (fair). The 2008 FIBI score was 61 (good) and the BMIBI score was 74 (good). The 2001 2001 BMIBI score was 65 (good). The 2002 Fisheries FIBI score was 67 (good). The aquatic life use support was assessed as fully supporting (=FS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports. The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008. The FIBI BIC for this ecoregion is 36 and the BMIBI BIC for this ecoregion is 51. This segment passed the FIBI BIC 3/3 times and passed the BMIBI BIC 2/3 times in the last 14 years.

This aquatic life assessment is now considered "evaluated" based on a change in the 2010 IDNR assessment methodology. IDNR now requires a segment have two or more biological samples collected from the segment in multiple years over a five-year period to be considered “monitored”. This segment had multiple samples collected in the previous 14 years (2001-2014); however, the samples were not collected during a five-year period. However, despite this change in assessment methodology and type, this waterbody remains in IR Category 2a.

Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream segment.

Monitoring and Methods

Assessment Key Dates

8/20/2008

Biological Monitoring

9/27/2012

Biological Monitoring

7/30/2001

Biological Monitoring

8/6/2002

Biological Monitoring

Methods

150

Monitoring data more than 5 years old

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

380

Quantitative physical habitat assessment