Underground rivers are a part of urban utility services communication that make our life comfortable. But we can't live in a city full of rivers or canals. Moscow has hundred of them and they are hidden underground in concrete manifolds.
Public utilities do not often do their work as they should and do not control the condition of the rivers. Some car washes, for example, discharge dirty water with chemicals into underground rivers. It may spoil a manifold, soil, ecology.
Neglinka is the most famous river in Moscow, it falls into the Moskva river
Neglinka used to be clean but by the end of the 18 century the population of Moscow grew pretty much and a lot of dirt and trash flowed into the river. After the fire of 1812 it was hidden in the manifold because it simply became stinky. The manifold, however couldn't manage with the streams of water and floods occured rather often.