Differentiate between concentration-based and load-based permit limits and provide a scenario for using each.

• A. Concentration-based limits specify the concentration in the effluent.
• B. Load-based limits specify the mass of pollutant discharged per time.
• C. They are interchangeable and have no impact on permit decisions.
• D. Use load-based limits when water body assimilative capacity is considered or facility flow varies.

Answer: (D)