help getting rid of water snakes

[boilermaker27]

I live in a private subdivision of over 725 homes and three lakes. The dam at our main lake was eroding and the DNR told us to plant these large reed like plants along the dam to prevent erosion. Problem is that our beach is right next to the dam and there are an unknown number of water snakes in the reeds right next to the beach. The snakes swim right through the swim area, two days ago there were about 40 people in the water and one of the snakes swam right through the swim area, and in about 15 seconds everyone was scrambling for the beach. I am not afraid of snakes and understand snakes, but most people are deathly afraid of snakes. Is there any repellent or anything that we can use to drive the snakes out of this portion of reeds? I have heard mothballs may work but some say they do, and some say they don't.