Water: Water Quality Standards Academy
Basic Course: Supplemental Topics (NPDES Permit 12)
- Listing Impaired Waters and Developing TMDLs
- Monitoring & Assessment
- NPDES Permit Program
- Point Source Control
- Permitting Authority
- Types of Permits
- Categories of Permits
- Permit Components
- Key Considerations
- Technology-Based Determination
- Water Quality-Based Determination
- WQBELs Process
- Step 1: Identify WQSs
- Step 2: Assess Concentration
- Pollutants of Concern
- Critical Conditions
- Dilution/Mixing Allowance
- Step 3: Establish Need
- Step 4: Calculate Limits
- Human Health Ambient Water Quality Criteria
- Aquatic Life Criteria
Establishing WQBELs: Step 2—Characterize the Effluent & Receiving Water
This next step in assessing the need for water quality-based effluent limits involves a sequence of four tasks, which are listed below and described in the pages that follow:
- Identify pollutants of concern in the effluent.
- Establish whether dilution/mixing of effluent in receiving waters is allowed by the State/Tribe’s water quality standards.
- Identify critical conditions for effluent and receiving water modeling.
- Establish the appropriate dilution allowance or mixing zone for each pollutant of concern.