Catfish Creek IA 01-TRK-124

mouth (Dubuque Co.) to confluence with South Fork Catfish Cr. Dubuque 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: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 3/31/2016 3:24:38 PM
Updated: 10/5/2016 7:34:27 AM

Use Support

Class A1

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

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2012

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

TMDL Priority

Tier III

Class BWW1

Aquatic Life - Warm Water Type 1

Not Assessed

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 Class A1 (primary contact recreation) uses remain assessed (monitored) as “not supported” (IR 5p) due to levels of indicator bacteria (E. coli) that exceed state water quality criteria. The assessment of support of the Class B(WW1) aquatic life uses is changed from “fully supporting” to “not assessed (IR 3a) due to the lack of recent data upon which to base an assessment. Fish consumption uses remain "not assessed" (IR 3a) due to the lack of fish contaminant monitoring in this stream reach. The source of data for this assessment is the results of monitoring from May to October 2010 at Station WQ-01 of the Catfish Creek Watershed Project (quality assurance/project plan available upon request).

Assessment Explanation

The Class A1 (primary contact recreation) uses remain assessed (monitored) as "not supported" based on levels of indicator bacteria that exceeded state water quality criteria. The geometric mean of indicator bacteria (E. coli) in the 11 samples collected approximately every two weeks during the recreational season of 2010 at Site WQ-01 of the Catfish Creek Watershed Project (2,390 orgs/100 ml) far exceeded the Iowa water quality criterion to protect primary contact recreation uses (126 orgs/100 ml). Nine of the 11 samples (82%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if the geometric mean is greater than 126 orgs/100 ml., the primary contact recreation uses are "not supported" (see pgs 3-33 to 3-35 of U.S. EPA 1997b).

The Class B(WW1) uses are considered “not assessed” due to the lack of recent data upon which to base an assessment. Previous assessments were based on results of IDNR/LTRMP chemical/physical monitoring at station CF00.3M from January 2000 through September 2004. According to Iowa DNR’s assessment/listing methodology, as data age beyond 10 years, they are no longer considered appropriate for characterizing current water quality conditions. Thus, because the most recent data available for this assessment segment were collected more than 10 years ago, the aquatic life uses of this segment are now considered “not assessed”.

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

Monitoring and Methods

Assessment Key Dates

5/12/2010

Fixed Monitoring Start Date

10/27/2010

Fixed Monitoring End Date

Methods

220

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

420

Indicator bacteria monitoring