It is because if there is any waster or dust particles in the water .To clean the water it is using screening.
screening
screening
A river is a large natural path water travels in to reach an ocean or other large body of water. A reservoir is usually a man-made lake of sorts. The water does not flow and its purpose is simply to wait until it can be taken for human use.
Transportation
the river provides water for the towns people in asia.
Rivers are made either from seas or from streams far in the mountains.
The water from the Murray River serves a variety of purposes.irrigation for crops (its main purpose)watering of livestockwater storage and town water suppliestourismtransportation of goodsrecreation and water sportsindustrial usefishing
A watershed is not a building, it is an area of land that contributes run off to a given lake, stream, river or other body of water. It's purpose is to supply water to the water body. (From Ask.com)
No amount of water can mask or clean a drug screening.
no step is taken by the government till now because government is corrupted
It acts as a water pipeline via the Colorado river. It provide recreational opportunity,
Water taken from the River Nile is used to irrigate crops grown along the Nile valley.