Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Silver Creek IA 01-WPS-363

from Crystal Cr. (aka Clear Cr.) (S23 T81N R3E Clinton Co.) to confluence with Negro Cr. in S27 T82N R3E Clinton Co.

Assessment Cycle
2004
Result Period
2000 - 2002
Designations
Assessment Methodology
Assessment Type
Monitored
Integrated Report
Category 1
Legacy ADBCode
IA 01-WPS-0070_2
Overall Use Support
Threatened
Aquatic Life Use Support
Threatened
Documentation
Assessment Comments

Assessment is based on results of (1) a 1997 fish survey conducted by the IDNR Fisheries Bureau in DeWitt city park and (2) IDNR/UHL biological (biocriteria) sampling in 1998 (Fish IBI= 40(fair), BM-IBI= 55(fairly good)).

Basis for Assessment

SUMMARY:  The Class B(LR) aquatic life uses remain assessed (monitored) as "fully supported / threatened" (minor impacts) based on results of (1) the 1997 fish survey conducted by the IDNR Fisheries Bureau and (2) the 1998 biological (biocriteria) sampling conducted by IDNR/UHL.   This is the same assessment as that developed for the 2002 reporting cycle.

EXPLANATION:  The aquatic life uses remain assessed as "fully supported / threatened" based on results of the biological monitoring conducted on this stream segment in 1997 and 1998 (see assessments for the 1998 and 2000 reports).   These data are less than five years old and, according to IDNR's methodology for Section 305(b) assessments, are thus appropriate for characterizing current water quality conditions.

Monitoring and Methods
Assessment Key Dates
7/22/1998 Biological Monitoring
7/22/1998 One-time Chemical Monitoring
8/1/1997 Biological Monitoring
Methods
220 Non-fixed station physical/chemical monitoring (conventional pollutant only)
315 Regional reference site approach
320 Benthic macroinvertebrate surveys
330 Fish surveys
380 Quan. measurements of instream parms-- channel morphology-- floodplain-- 1-2 seasons-- by prof
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 1
BioIntegrity Fair
Causes and Sources of Impairment
Causes Use Support Cause Magnitude Sources Source Magnitude
Other habitat alterations Aquatic Life Support Not Impairing
  • Agriculture
  • Bank or Shoreline Modification/Destabilization
  • Channelization
  • Habitat Modification (other than Hydromodification)
  • Hydromodification
  • Not Impairing
  • Not Impairing
  • Not Impairing
  • Not Impairing
  • Not Impairing
Siltation Aquatic Life Support Not Impairing
  • Agriculture
  • Bank or Shoreline Modification/Destabilization
  • Channelization
  • Habitat Modification (other than Hydromodification)
  • Hydromodification
  • Not Impairing
  • Not Impairing
  • Not Impairing
  • Not Impairing
  • Not Impairing