Deer Creek IA 02-CED-591

mouth (S23 T99N R18W Mitchell Co.) to the Mitchell-Worth county line (west line S6 T100N R18W Mitchell 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 2014 - 2016
Stream/River Water Quality Data	CY 2014 - 2016
Lake Water Quality Data	CY 2012 - 2016
Biological Sampling Data	CY 2012 - 2016*
Fish Kill Data	CY 2012 - 2016
Fish Tissue Sampling Data	CY 2012 - 2016
Continuous Dissolved Oxygen Sampling Data	CY 2012 - 2016
*Biological sites sampled in both 2011 and 2015 were also assessed.

Open Segment Map
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Cycle: 2018
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 5/13/2019 2:16:51 PM
Updated: 7/18/2019 12:59:33 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Partially Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Partially Supported

Impairment Code

5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Special project/study

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 primary contact recreation uses are assessed (monitored) as “partially supported" due to levels of indicator bacteria that slightly exceed state criteria. The Class B(WW2) aquatic life uses are assessed (monitored) as “fully supported” based on results of DNR/SHL biological sampling in 2008, 2010 and 2013 and based on results of chemical/physical water quality monitoring in 2012 and 2013. The sources of data for this assessment are (1) the results of ambient physical/chemical water quality monitoring conducted at station 15660007 on Deer Creek at Dancer Avenue from 2015 through 2016, (2) results of bacteria monitoring at station 15660007 from 2014 through 2016 and (3) results of 2008, 2010 and 2013 DNR/SHL biological sampling near Carpenter.

Assessment Explanation

The presumptiveClass A1 (primary contact recreation) uses are assessed (monitored) as "partially supported" based on levels of indicator bacteria that exceeded state water quality criteria. The geometric means of indicator bacteria (E. coli) in the 18 samples collected during the recreational seasons of 2014 through 2016 at station 15660007 on Deer Creek at Dancer Avenue were as follows: the 2014 geometric mean was 190 orgs/100 ml, the 2015 geometric mean was 241 orgs/100 ml, and the 2016 geometric mean was 166 orgs/100 ml. All three recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml. Seven of the combined 18 samples (39%) exceeded Iowa’s Class A1 single-sample maximum criterion of 235 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and Iowa DNR’s assessment/listing methodology, if the geometric mean is greater than 126 orgs/100 ml., the primary contact recreation uses should be assessed as "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b). Thus, because at least one recreation season geometric mean exceeded criteria for Class A1 uses, these uses are assessed as "partially supported."

Both chemical/physical and biological data suggest that the Class B(WW-2) aquatic life uses should be assessed (monitored) as “fully supported.”Results of chemical/physical water quality monitoring at station 15660007 on Deer Creek at Dancer Avenue suggest “full support” of the aquatic life uses. Monitoring showed no violations of Class B(WW2) water quality criteria for 5 Dissolved Oxygen samples (minimum = 6.6 mg/L), 11 pH samples (range = 7.5 to 8.4), or 11 Temperature samples (maximum = 23°C) occurred during monitoring from July 2015 to October 2016. According to U.S. EPA guidelines for Section 305(b) water quality assessments (U.S. EPA 1997b, page 3-17), the EPA guidelines allow up to 10% violations of these conventional parameters before impairment of water quality is indicated. Thus, these results thus suggest “full support” of the Class B(WW2) aquatic life uses.

The assessment of the Class B(WW2) aquatic life uses was also based on biological data collected in 2008, 2010 and 2013 as part of the DNR/SHL stream biocriteria project. The 2008 FIBI score was 73 (excellent) and the BMIBI score was 91 (excellent). The 2010 BMIBI score was 71 (good). The 2013 FIBI score was 76 (excellent) and the BMIBI score was 60 (good). The aquatic life use support was assessed (monitored) 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 riffle habitat FIBI BIC for this ecoregion is 65 and the natural substrate BMIBI BIC for this ecoregion is 70. This segment passed the FIBI BIC 2/2 times and passed the BMIBI BIC 2/3 times in the last nine years. This assessment is considered "evaluated" because there weren't two or more samples collected from this segment in multiple years in the most recent five year period (2012-2016).

Monitoring and Methods

Assessment Key Dates

8/25/2008

Biological Monitoring

8/18/2010

Biological Monitoring

8/21/2013

Biological Monitoring

4/22/2014

Fixed Monitoring Start Date

10/10/2016

Fixed Monitoring End Date

Methods

150

Monitoring data more than 5 years old

240

Non-fixed station physical/chemical (conventional + toxicants)

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

380

Quantitative physical habitat assessment

420

Indicator bacteria monitoring