Relationships between pollutant discharge and water quality in the rivers from “better” to “worse” water quality

- BOD has been “better” concentrations in the Brisbane River since the 1970s.
- Nutrient concentrations has not been necessarily “better.”
- Daily-basis relationship of pollutant discharge and water quality has been complicated.
- Long-term relationship has been perturbation or dynamic equilibrium change.
- A comprehensive hypothesis is presented based on the relationships in the three rivers.