- water
- water-quality
- permitting
A wasteload allocation is the portion of a total maximum daily load handed to point sources — the permitted dischargers, as distinct from the load allocation given to diffuse runoff. It is the mechanism that turns a watershed-scale pollutant budget into an enforceable limit at a specific pipe.
A state implements a WLA by writing it into the discharger's NPDES permit as a water-quality-based effluent limit. So a WLA is where the abstract budget becomes concrete: it determines whether a plant on an impaired reach has any load headroom to absorb growth, or whether a new industrial or municipal load forces an offset somewhere else in the watershed. When a reach's WLAs are already fully subscribed, an added discharge has nowhere to go on paper.