Iowa DNR
Iowa DNR

ADBNet

Water Quality Assessments
Impaired Waters List

Little Rock River IA 06-BSR-1799

from confluence with Otter Cr. (NW 1/4 S21 T98N R44W Lyon Co.) to confluence with Argo Slough in S17 T99N R43W Lyon Co.

Assessment Cycle
2000
Result Period
1996 - 1998
Designations
Assessment Methodology
Assessment Type
Monitored
Integrated Report
Category 0
Legacy ADBCode
IA 06-BSR-0060_2
Overall Use Support
Threatened
Aquatic Life Use Support
Threatened
Documentation
Assessment Comments

Assessment is based on results of 1996 Biocriteria sampling: Fish IBI=40 (fair).

Basis for Assessment

The assessment was based on data collected in 1996 as part of the DNR/UHL stream biocriteria project.   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 (F-IBI) and a benthic macroinvertebrate index (BM-IBI).   The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum).

Only the Fish-IBI was calculated for this assessment.   The F-IBI score was 40 (fair).   The aquatic life use support was assessed as fully supported / threatened (=FST), based on a comparison of the F-IBI score with biological assessment criteria established specifically for the 2000 Section 305(b) report.   The biological assessment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-1998.

Monitoring and Methods
Assessment Key Dates
9/5/1996 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 Fair