2016 assessment for Middle Bear Creek

Middle Bear Creek IA 01-UIA-256

mouth (S14 T100N R7W Winneshiek Co.) to north line of S16 T100N R7W Winneshiek Co.

2016
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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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

8/24/2016 10:22:51 AM by

Updated

10/5/2016 8:32:43 AM by

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class A2

Presumptive Use

Recreation - Secondary contact

Not Assessed

Class BCW1

Aquatic Life - Cold Water Type 1

Fully Supported

Class HH

Human Health -

Not Assessed

General Use

General Use water -

Not Assessed

303(d) Delistings for this Cycle

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 (primary contact recreation) uses and presumptive Class A2 (secondary contact recreation) uses remain "not assessed" (IR Category 3a) due to the lack of data for indicator bacteria upon which to base an assessment. The Class B(CW1) coldwater aquatic life uses are assessed (evaluated) as "fully supported" (IR 2a) based on the 2003 and 2007 IDNR/SHL biological sampling data and the January 2016 summary of trout reproduction in Iowa streams as prepared by the IDNR Fisheries Bureau. Fish consumption uses remain "not assessed" (IR 3a).

Assessment Explanation

The assessment of the Class B(CW1) aquatic life uses was based on data collected in 2003 and 2007 as part of the IDNR/SHL coldwater stream sampling project. A series of biological metrics which reflect coldwater stream water quality and habitat integrity were calculated from the biological sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa that were collected in the stream sampling reach. The biological metrics were combined to make a coldwater benthic index (CBI). The index ranks the biological integrity of a coldwater stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2003 CBI score was 65 and the 2007 CBI score was 65. The aquatic life use support was assessed (evaluated) as fully supporting (=FS), based on a comparison of the CBI score with biological impairment criteria (BIC) established for the 2012 Section 305(b) report. The biological impairment criteria were determined from a statistical analysis of data collected at coldwater stream reference sites from 1994-2011. The CW BIC is 60 and this segment passed the CW BIC 2/2 times in the last 12-year period (2003-2014); therefore, this is considered an evaluated assessment.

In addition, based on an updated summary of trout reproduction in Iowa streams prepared by the IDNR Fisheries Bureau in January 2016, the Class B(CW1) uses are assessed as "fully supported". According to the updated summary, Middle Bear Creek is in the group of Iowa coldwater streams that supports natural reproduction of trout. Based on results of surveys by the IDNR Fisheries Bureau, this stream is placed in the category of Iowa trout streams that exhibit fairly consistent natural reproduction and maintain a viable population of brook and brown trout without any stocking (Category I).

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

Monitoring and Methods

Assessment Key Dates

1/1/2016

Biological Monitoring

7/17/2007

Biological Monitoring

7/27/2003

Biological Monitoring

Methods

120

Surveys of fish and game biologists/other professionals

150

Monitoring data more than 5 years old

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

380

Quantitative physical habitat assessment