Stream Classification for TMDL
Assessment Using a Dimensionless, Reference Reach Approach
Bruce Wilson, Professor
John Nieber, Professor
James A. Perry, Professor and Head, Fisheries and Wildlife
Bruce Vondracek, Professor, Fisheries and Wildlife
Joe Magner, Minnesota Pollution Control Agency
Greg Johnson, Minnesota Pollution Control Agency
Funding Source
U.S. Environmental Protection Agency – STAR Grant Objective
The overall goal of the proposed project is to develop a simple
classification system that is useful in TMDL assessment. Research
objectives are to:
- Investigate the relationship between indicators of stream
health and localized stream characteristics,
- Develop and evaluate dimensionless curves using reference
reach values as a tool for stream classification and TMDL
assessment, and
- Propose and test a stream classification system using
the prediction intervals of the dimensionless curves.
Need or Impact
The classification system will be used by states to prioritize
efforts related to TMDL programs. The approach is well suited
for considerations of changes in land use and other watershed
practices.
Project Status
The classification method uses regional reference reaches
to account for complex factors related to precipitation, land
use, soil, and geology. Dependent variables of stream health
and independent variables of localized stream characteristics
are converted into dimensionless form by normalizing their
values by those of the reference reach. Dimensionless relationships
are obtained using regression analyses. The variance of predicted
values are used to compute three different prediction intervals.
These intervals are then used to classify streams within a
given region. Development and evaluation of the proposed classification
system will be done using a large data set of stream stations
gathered within four considerably different regions in Minnesota.
An independent data set will be used for testing.
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