Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

East Fork Unnamed Tributary to Arbor Lake IA 03-NSK-1874

mouth (NW1/4 SE1/4 S17 T80N R17W Poweshiek Co.) to headwaters at 1st Avenue Grinnell (T80 R16W Sec17 Poweshiek Co.)

Assessment Cycle
2006
Result Period
2002 - 2004
Designations
General Use
Assessment Methodology
Assessment Type
Evaluated
Integrated Report
Category 3b
Legacy ADBCode
IA 03-NSK-0071_0
Overall Use Support
Not supporting
Aquatic Life Use Support
Documentation
Assessment Comments

Assessment based on 2003 TMDL data: FIBI = 0 (poor). FIBI BIC = 36.

Basis for Assessment

SUMMARY:  This evaluated biological assessment was based on data collected in 2003 as part of the DNR/UHL stream TMDL sampling.   A series of biological metrics that 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 fish species collected in the stream sampling reach.   The biological metrics were combined to make a fish community index of biotic integrity (FIBI).   The index ranks the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum).   The 2003 FIBI score was 0 (poor).  The aquatic life use support was assessed (evaluated) as Not Supporting (= NS), based on a comparison of the FIBI score with biological impairment criteria (BIC) established from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2004.   The FIBI BIC for this ecoregion is 36.   Even though this site failed to meet the FIBI BIC, it is uncertain as to whether or not this segment is meeting the aquatic life criteria because it is a small general use stream and doesn’t fall in the calibrated watershed size.

Monitoring and Methods
Assessment Key Dates
10/10/2003 Biological Monitoring
Methods
220 Non-fixed station physical/chemical monitoring (conventional pollutant only)
315 Regional reference site approach
330 Fish surveys
380 Quan. measurements of instream parms-- channel morphology-- floodplain-- 1-2 seasons-- by prof
Monitoring Levels
Biological 3
Habitat 4
Physical Chemistry 1
Toxic 0
Pathogen Indicators 0
Other Health Indicators 0
Other Aquatic Life Indicators 0
# of Bio Sites 1
BioIntegrity Poor
Causes and Sources of Impairment
Causes Use Support Cause Magnitude Sources Source Magnitude
Cause Unknown Overall Use Support High
  • Source Unknown
  • High