Leads and alcohol at Bohernabreena

Tess takes a moment out for a swim while walking at the Bohernabreena Waterworks on St Patrick's Day.

The picture below is at the Waterworks. Does it mean alcohol must not be abused at the lakes or is it saying all alcohol is not allowed? Presumably the second meaning. But it's not clear.

According to the sign Tess should be on a lead.