I want to know the answer to the following question:
What causes increased pollution and levels of bacteria such as E. coli to rise in the Yarra River and its tributaries?
All the background I'm provided with is that "Other major pollution problems in Melbourne include levels of bacteria including E. coli in the Yarra River and its tributaries caused by septic systems, as well as litter.". Is that enough to answer the question?
Answer: yes