Drainage Ditch 71 IA 03-SSK-963

mouth (SE1/4 S11 T86N R24W Hamilton Co.) to confluence of Rahto Brach Ditch and Loop Branch Ditch in SE1/4 SE 1/4 S18 T87N R24W Hamilton Co.

This is a Legacy Assessment. Prior to 2004, assessments were developed under a methodology that pre-dated the Integrated Report guidelines.

Assessment Cycle

2002

Result Period

1998 - 2000

Designations

Assessment Methodology

2002 Methodology Document

Assessment Type

Monitored

Integrated Report

Category 0

Legacy ADBCode

IA 03-SSK-0100_0

Overall Use Support

Not supporting

Aquatic Life Use Support

Not supporting

Documentation

Assessment Comments

Assessment is based on (1) 1997 DNR/UHL bioassessment (Fish IBI= 20 (poor), BM-IBI= 42 (fair)) and (2) occurrence of a fish kill in August 1999.

Basis for Assessment

The assessment was based on the 1997 biological sampling results (see comments for 2000 assessment). The aquatic life use support continued to be assessed as not supporting (=NS), based on a comparison of the F-IBI and BM-IBI scores with biological assessment criteria established specifically for the 2002 Section 305(b) report. The biological assessment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2001.

Monitoring and Methods

Assessment Key Dates

8/19/1999	Fishkill
10/9/1997	Biological Monitoring

Methods

330	Fish surveys
380	Quan. measurements of instream parms-- channel morphology-- floodplain-- 1-2 seasons-- by prof
140	Incidence of spills and/or fish kills
220	Non-fixed station physical/chemical monitoring (conventional pollutant only)
315	Regional reference site approach
320	Benthic macroinvertebrate surveys

Monitoring Levels

Biological	4
Habitat	4
Physical Chemistry	1
Toxic	0
Pathogen Indicators	0
Other Health Indicators	0
Other Aquatic Life Indicators	0
# of Bio Sites	0
BioIntegrity	N/A

Causes and Sources of Impairment

Causes	Use Support	Cause Magnitude	Sources	Source Magnitude
Nutrients	Overall Use Support	Moderate	Source Unknown	Moderate
Nutrients	Aquatic Life Support	Moderate	Source Unknown	Moderate
Organic enrichment/Low DO	Overall Use Support	Moderate	Source Unknown	Moderate
Organic enrichment/Low DO	Aquatic Life Support	Moderate	Source Unknown	Moderate
Other habitat alterations	Overall Use Support	Moderate	Bank or Shoreline Modification/Destabilization Channelization Habitat Modification (other than Hydromodification) Hydromodification	Moderate Moderate Moderate Moderate
Other habitat alterations	Aquatic Life Support	Moderate	Bank or Shoreline Modification/Destabilization Channelization Habitat Modification (other than Hydromodification) Hydromodification	Moderate Moderate Moderate Moderate
Unionized Ammonia	Overall Use Support	Moderate	Spills	Moderate
Unionized Ammonia	Aquatic Life Support	Moderate	Spills	Moderate