Signs warning drivers to stay off the dunes on South Padre island went up Thursday.

Augusto Sanchez, a natural resource engineer with Cameron County, said the dunes create a natural barrier against coastal erosion that can also result in damage to houses and roads.

Now, the county is warning the public that driving on the dunes is a Class C misdemeanor, punishable with a fine of up to $200.

Watch the video above for the full story.