Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Farmers Creek IA 01-NMQ-94

mouth (S24 T85N R2E Jackson Co.) to confluence with unnamed tributary in W 1/2 NW 1/4 S8 T86N R3E Jackson Co.

Cycle
2018
Release Status
Final
Overall IR
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
5/9/2019 11:06:19 AM
Updated
8/14/2020 8:28:21 AM
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class BWW2
Aquatic Life - Warm Water Type 2
Partially Supported
Support Level
Partially Supported
Impairment Code
5b-t - Biological - tentative
Cause Magnitude
Slight
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2004
Impairment Rationale
Low Biotic Index
Data Source
Biological monitoring: Iowa DNR WQMA
TMDL Priority
Tier IV
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" due to the lack of information upon which to base an assessment. The Class B(WW2) aquatic life uses remain assessed (evaluated) as "fully supported" based on results of DNR/SHL biological sampling in 2007 and 2011-2013. Although the results of the biological sampling suggest (evaluated) "full support" of the aquatic life uses, this segment remains in IR Category 5b-t because the assessment used: (1) data older than five years (2007 and 2011) and (2) data collected outside the index period (7/15-10/15).

Assessment Explanation

The Class B(WW2) aquatic life uses are assessed (evaluated) as “fully supported” was based on data collected in 2007 and 2011-2013 as part of the DNR/SHL stream biocriteria and follow-up sampling projects. A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the biocriteria sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species that were collected in the stream sampling reach. The biological metrics were combined to make a fish community index of biotic integrity (FIBI) and a benthic macroinvertebrate index (BMIBI). The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2007 BMIBI scores were 53 (fair) and 61 (good). The 2011 FIBI score was 57 (good) and the BMIBI score was 49 (fair). The 2012 FIBI score was 59 (good) and the BMIBI score was 50 (fair). The 2013 FIBI score was 64 (good) and the BMIBI score was 57 (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 5/5 times and passed the BMIBI BIC 3/5 times in the last 10 years.

This aquatic life assessment is now considered "evaluated" based on a change in the 2010 DNR assessment methodology. DNR now requires a segment have two or more biological samples collected from the segment in multiple years over a recent five-year period to be considered “monitored”. This segment had multiple samples collected in the previous five years (2012-2016); however, the data were inconclusive and could not complete the assessment. To complete the assessment, data older than five years were used (2007 and 2011); therefore, the assessment was changed from "monitored" to "evaluated."Despite this change in assessment methodology and type, this waterbody remains on the 2018 list of impaired waters as a fully supporting - evaluated waterbody.

Monitoring and Methods
Assessment Key Dates
8/8/2007
Biological Monitoring
8/14/2012
Biological Monitoring
8/13/2013
Biological Monitoring
Methods
150
Monitoring data more than 5 years old
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys