muddy water; turbid water
Refers to water that is cloudy or discolored due to suspended particles, often after rain or disturbance.
After the rain, the river was full of muddy water.
Compound of 濁り (にごり, 'muddiness, turbidity'), the noun form of verb 濁る (にごる, 'to become muddy'), and 水 (みず, 'water').