Water: Water Quality Standards Academy
Basic Course: Supplemental Topics (NPDES Permit 10)
- 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: A Four-Step Process
EPA has identified the following steps to assess the need for water quality-based effluent limits (WQBELs) and to then establish the limits as necessary based on the assessment:
Step 1. Identify applicable water quality standards.
Step 2. Characterize the effluent and receiving water.
Step 3. Determine the need for parameter-specific WQBELs.
Step 4. Calculate parameter-specific WQBELs.
Following these steps will enable States/Tribes to implement water quality standards in NPDES permits based on:
- Knowing the current water quality standards, including any changes.
- Being familiar with water quality standards implementation policies.
- Using procedures adopted by the permitting authority to establish limitations that are as stringent as necessary to attain the State/Tribe’s water quality standards.
Key Point. The CWA requires effluent limits in NPDES permits that will ensure compliance with water quality standards. (CWA Section 301(b)(1)(C)) These limits are generally referred to as WQBELs.
This section of the module considers the four-step process in more detail.