In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 

Let me give you an example:  Magma rises from deep in the earth. The magma goes into volcanos. The volcanos pressure the magma upwards. The pressure causes the magma to push through the surface of the volcano. The lava cools. The lava forms new rock. New magma is pressured to the surface of the volcano. The volcano bursts through the rock the formed after the last eruption. 
The answer to this example can be:  magma ,lava ,new rock 
Here is why: The entities are present in the process paragraph and they undergo state change. So, this is a positive example.

OK. solve this:
There is a lot of rain. Water levels of a river or lake get higher. Water builds up on the ground. Water covers streets. Water goes into houses. The rain or other source of water stops. Water flows into streams. The rest of the water evaporates. 
Answer:
rain ,water ,streams ,water levels 