The TMDL Program

1
Benthic TMDL for Stroubles Creek
Overview and Research Plans
Biological Systems Engineering Department Virginia
Tech
2
The TMDL Program

• TMDL Total Maximum Daily Load
• A process to examine water quality
• Clean Water Act, USEPA
• General Standard for Aquatic Life
• Benthic Macroinvertebrates insects that live on
  the stream bottom

3
Stroubles Creek Watershed
4
Stroubles Creek Benthic Impairment

• Stressor Analysis
• Water Quality
• pH, dissolved oxygen, temperature, sediment,
  toxics
• Benthic Metrics
• number, diversity, pollution tolerance
• Qualitative Analysis
• habitat

5
The Stressor Sediment

• No numeric standard
• Reference Watershed Approach

6
Determining TMDL Targets
TMDL Target Load
7
Modeling for TMDLs

• User Defined Inputs

• Model Defined Relationships

• Computer Generated Outputs

Runoff Sediment
8
Research Questions

• Only one reference?
• Reference approach One to One
• Categorization evaluation One to Many
• My research One to Some

9
Research Questions

• The Model
• Several choices of models
• GWLF
• Aquatox

10
GWLF Generalized Watershed Loading Functions
Components of GWLFs Daily Water Balance
Yields stream flow, sediment load
11
EPAs Aquatox
Yields biomass and water quality parameters (DO,
sediment)
12
Research Questions

• Combination of reference watersheds and different
  models
• Effect of potential changes in the watershed

13
Questions?
Rachel C. Wagner Biological Systems Engineering
Stroubles Creek by Pat Bevans