Water Effect. Looks pretty white, but it gets almost milky white when you leave them for 1 day. Water Effect is to express waves etc at the water surface.
Making the bottom of a lake by some plaster sheets. Cut some 4mms thick board for the lakeside to stop water.
Trial for water gradation. Lake Aoki looks like green but Azusa river looks like blue.
Looks different when you put some realistic water there.