I have long wanted to write about this. Sometimes on the water there are such things:

for this example
UseOriginalPostProcessing=true
UseOriginalObjectsProcessing=true
UseDefferedRendering=false
in game settings enable only sky reflection.
First image - reflection bug on water after load.
Two - after Shift+F12 and again Shift+F12
Three - after Shift+F12 and again Shift+F12. Bug disappeared.
Five - appeared after moved.
Especially bright it at night. Some bright reflection... although UseOriginal is true. Standard ENB presets have this bug too with UseOriginal false and all water reflection.