Is there a snake deterrent

No, Snake Repellents do not work. In general snake repellents are made up of ingredients that strike humans as powerful or just plain stinky. Many have napthalene as a main ingedient - the same ingedient that makes mothballs stink. But napthalene is not approved to be used outdoors to repel snakes, and there is no evidence or reason to think it works anyway. The one university study that purveyors of these snake oils point to has been shown to be poorly designed and proves nothing.

Any substance one puts on their lawn and garden to repel snakes would just be washed away with the first dew or rain anyway.

For a better understanding of ways to get rid of snakes see;

http://tinyurl.com/snake-repellents