Stains on cinder block fence
I have a cinder block fence and on the outside wall which fall on the street there are stains most likely from water/rain sipping from the yard. I have a desert landscape and just couple bushes, watering is done by the drip system 3 times a week, when the water dripping system start the ground barely gets wet. I have use CLR I bought from home depot that did not work. I used 50/50 bleach water few times which also did not work. I am in HOA sub-division so have got violation notice. I have asked them if they have any suggestion on how to remove this and they have not offered me anything.
Does anyone here have suggestion on how to get rid of the stains. I upload a image file hope it shows up.
Thanks for help and suggestion in advance.