threats to waterother than pollution?

Answer 1

Over fishing of the living organisms in water,
over consumption of drinking water,
mismanagement of stormwater runoff (resulting in flash floods),
construction in flood zones

Answer 2

There are a lot of threats to the worlds waterways and most do not fall under what we usually consider pollution. These include things like turbidity (sediments), channelization of streambeds, and over fishing. There is also the diversions of complete rivers for irrigation, which ends up killing the ecosystems that relied on that river. We can't really stop these practices but we can educate people to conserve the water they have so we don't have to scrap more from other sources.