Bear Creek IA 01-UIA-251

mouth (S1 T99N R6W Allamakee Co.) to confluence with N. Bear Cr. in S25 T100N R7W Winneshiek 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: 5/17/2016 10:53:21 AM
Updated: 10/4/2016 12:19:44 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

Watershed project monitoring

TMDL Priority

Tier III

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 are assessed (monitored) as “partially supported” due to levels of indicator bacteria that exceed state water quality criteria (IR 5p). The Class B(WW1) aquatic life uses are assessed as “fully supporting” (IR 2a) based on results of monitoring from 2012-2014. Fish consumption uses remain “not assessed” due to the lack of fish contaminant monitoring in this assessment segment. The source of data for this assessment is the results of chemical, physical and bacterial monitoring at Site 25 of the Upper Iowa River Watershed (UIRW) project (STORET No. NEIARCD 190050002) from April 2012 through October 2014.

Assessment Explanation

The Class A1 (primary contact recreation) uses are assessed as "partially supported" based on levels of indicator bacteria that exceeded state water quality criteria. The geometric mean of indicator bacteria (E. coli) in the 20 samples collected during the recreational seasons of 2012 through 2014 at the IDNR ambient monitoring station UIRW 25 exceeded the Iowa water quality criterion to protect primary contact recreation uses. All three recreation season (March-November) geometric means from 2012-14 slightly exceeded Iowa’s Class A1 water quality criterion of 126 orgs/100 ml: the 2010 geometric mean was 131 orgs/100 ml, the 2013 geometric mean was 336 orgs/100 ml, and the 2014 geometric mean was 340 orgs/100 ml. Nine of the 20 samples (45%) 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 a recreation season geometric mean is greater than the water quality criterion of 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).

The Class B(WW1) warmwater aquatic life uses are assessed as “fully supporting”. Monitoring from 2012 to 2014 at Upper Iowa River Watershed Site 25 (STORET station 190050002) included analysis of 14 samples for ammonia, pH, and temperature. There were no violations of the Class B(WW1) criteria for ammonia, pH or temperature in these samples. Thus, the results of ammonia monitoring in this stream segment from 2012-2014 suggest “full support” of the Class B(WW1) uses. .

The fish consumption uses remain “not assessed” due to the lack of water quality information upon which to base an assessment.

Monitoring and Methods

Assessment Key Dates

4/3/2012

Fixed Monitoring Start Date

10/7/2014

Fixed Monitoring End Date

Methods

220

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

420

Indicator bacteria monitoring