this is a spill
this is a nitrogen problem
this is duckweed
this is an overgrowth of algae

this is natural iron
this is evidence of lead contamination
this is a spill
this is toxic algae

this water is unsafe and needs to be boiled because it contains high levels of harmful bacteria
this water is unsafe and needs to be boiled because it contains high levels of harmful viruses
this water is unsafe and needs to be boiled because it contains high levels of harmful parasites
all of the above

nothing! This is pristine alpine water
the algae growth on the right of the picture means this water is very contaminated
not sure what is in this water
high levels of minerals due to all the rocks

since this stormwater goes into a river, it must be pretty clean
there are a lot of dissolved and suspended contaminants in stormwater
the bubbles mean this water is rich in oxygen and good for fish habitat
low levels of any contaminants since the large volumes of stormwater dilutes the contaminants