Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Missouri River IA 06-WEM-1720

from confluence with Little Sioux R. (Harrison Co.) to confluence with Elm Cr. at river mile 691.0 at Decatur NE (=S18 T83N R46W Monona Co.).

Assessment Cycle
2002
Result Period
1998 - 2000
Designations
Assessment Methodology
Assessment Type
Evaluated
Integrated Report
Category 0
Legacy ADBCode
IA 06-WEM-0040_1
Overall Use Support
Partial
Aquatic Life Use Support
Partial
Fish Consumption
Not assessed
Primary Contact Recreation
Not assessed
Documentation
Assessment Comments

Assessment is based on (1) surveys of Nebraska fisheries biologists and (2) consultation with DNR staff.

Basis for Assessment

[Note:  For the 2002 report, the previous waterbody segment for the Missouri River (IA 06-WEM-0040-0), which extended 63 miles from the Little Sioux River to the Big Sioux River, was split into three subsegments:  (1) Little Sioux River to Elm Creek near Decatur, NE (near Onawa in Monona Co.) (IA 06-WEM-0040-1 - this one), (2) Elm Creek to Omaha Creek Ditch near Homer, NE (near Salix in Woodbury Co.) (IA 06-WEM-0040-2), and (3) Omaha Creek Ditch to the Big Sioux River at Sioux City, Woodbury County.  (IA 06-WEM-0040-3).   See previous assessments from this subsegment for previous Section 305(b) assessments for the original 63-mile river segment of the Missouri River.]

SUMMARY:  The Class A (primary contact recreation) uses remain "not assessed."  The Class B(WW) aquatic life uses remain assessed as "partially supported."  The fish consumption uses are "not assessed."  EXPLANATION:  The Class A uses remain "not assessed" due to the lack of monitoring data for indicator bacteria for this reach of the Missouri River.   The Class B(WW) uses remain assessed as "partially supported" based on the assessment developed for the 1998 and 2000 reports (i.e., habitat alterations and flow modifications that resulted from development of the river  for navigation uses in the mid-Twentieth Century).   This assessment was developed in consultation with the Missouri River fisheries biologist for the state of Nebraska.   Fish consumption uses are "not assessed" due to the lack of recent fish contaminant monitoring in this river segment.

Monitoring and Methods
Assessment Key Dates
Methods
120 Surveys of fish and game biologists/other professionals
Monitoring Levels
Biological 0
Habitat 0
Physical Chemistry 0
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
Flow alteration Overall Use Support Moderate
  • Flow Regulation/Modification
  • Moderate
Other habitat alterations Overall Use Support Moderate
  • Channelization
  • Moderate