Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

North Skunk River IA 03-NSK-858

from confluence with Middle Cr. (S35 T76N R14W Mahaska Co.) to the Mahaska/Poweshiek county line.

Assessment Cycle
2002
Result Period
1998 - 2000
Designations
Assessment Methodology
Assessment Type
Evaluated
Integrated Report
Category 0
Legacy ADBCode
IA 03-NSK-0020_1
Overall Use Support
Threatened
Aquatic Life Use Support
Threatened
Documentation
Assessment Comments

Assessment is based on 1996 biocriteria sampling: fish, 22 spp., 4 fams.; Fish IBI= 36(fair), BM-IBI= 53(fair).

Basis for Assessment

SUMMARY:  The Class B(LR) aquatic life uses remain assessed as "fully supported / threatened" (minor impacts).   The assessment category, however, is changed from "monitored" to "evaluated."  EXPLANATION:  Continue to use the assessment developed for the 1998 report (see above) that was based on results of the 1996 IDNR biocriteria assessment.   However, because these data are now considered too old (greater than five years) to accurately characterize current water quality conditions, the assessment category is changed from "monitored" (indicating an assessment with relatively high confidence) to "evaluated" (indicating an assessment with relatively low confidence).

Monitoring and Methods
Assessment Key Dates
10/7/1996 Biological Monitoring
Methods
330 Fish surveys
380 Quan. measurements of instream parms-- channel morphology-- floodplain-- 1-2 seasons-- by prof
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 1
BioIntegrity Fair
Causes and Sources of Impairment
Causes Use Support Cause Magnitude Sources Source Magnitude
Other habitat alterations Overall Use 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
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