If a river is polluted (crowded with) bugs and insects, is that a good thing or a bad thing

Question: If a river is polluted (crowded with) bugs and insects, is that a good thing or a bad thing
- Keywords:
  pollution,
  river
Asked by NBA Einstein GAA Genuis to William, Roberto, Karen, Jasmine, Chinna on 12 Nov 2018.
- William answered on 12 Nov 2018:
  
  It depends on the type of bug as some species can indicate pollution (like sludge worms) but things like mayfly larve will only live in really good quality water 🙂
- Karen answered on 13 Nov 2018:
  
  Usually if the river is clean you will have a wide range of insects, but if it’s very dirty you will mainly have the worms like William mentioned. We look at what insects are in the river to tell us whether it is clean or not 🙂

Question: If a river is polluted (crowded with) bugs and insects, is that a good thing or a bad thing