Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Big Muddy Creek IA 06-LSR-1637

mouth (S15 T96N R36W Clay Co.) to confluence with unnamed tributary in S17 T98N R35W Dickinson Co.

Cycle
2018
Release Status
Final
Overall IR
3 - Insufficient data exist to determine whether any designated uses are met.
Trend
Unknown
Created
5/17/2019 9:56:38 AM
Updated
7/30/2019 10:07:39 AM
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class BWW2
Aquatic Life - Warm Water Type 2
WINOFI
Impairment Code
3b-c - Use potentially biologically impaired based on calibrated IBI metrics.
Cause Magnitude
Moderate
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2012
Impairment Rationale
Low Biotic Index
Data Source
Biological monitoring: Iowa DNR WQMA
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 are assessed (evaluated) as "partially supported" based on results of DNR/SHL biological sampling in 2009 and 2013.

Assessment Explanation

The Class B(WW2) aquatic life uses are assessed (evaluated) as "partially supporting" based on data collected in 2009 and 2013 as part of the DNR/SHL stream biocriteria project. The 2013 FIBI score was 36 (fair) and the BMIBI score was 30 (poor). The 2009 FIBI score was 43 (fair) and the BMIBI score was 36 (fair). The aquatic life use support was assessed as partially supporting (=PS), 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 non-riffle habitat FIBI BIC for this ecoregion is 32 and the BMIBI BIC for this ecoregion is 62. This segment passed the FIBI BIC 2/2 times and passed the BMIBI BIC 0/2 times in the last eight 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 five-year period to be considered “monitored”. This segment had multiple samples collected in the previous six years; however, the multiple samples were not collected during a recent five-year period. According to DNR’s assessment/listing methodology, impairments based on “evaluated” assessments are of lesser confidence and are thus not appropriate for Section 303(d) listing (Category 5 of the Integrated Report). DNR does, however, consider these impairments as appropriate for listing under either Category 2b or 3b of the Integrated Report (waters potentially impaired and in need of further investigation).

Monitoring and Methods
Assessment Key Dates
9/15/2009
Biological Monitoring
8/27/2013
Biological Monitoring
Methods
150
Monitoring data more than 5 years old
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys
380
Quantitative physical habitat assessment