The cast sewer covers use imagery based on Coast Salish traditional design that represents the transformation of 4 frogs from eggs through the tadpole stage. The Art Underfoot competition was launched in April 2004 and culminated in an exhibition at the Roundhouse Community Centre. The competition invited anyone who lives, works, or goes to school in Vancouver to submit design ideas for new manhole covers. The Public Art Program received more than 640 entries from Vancouverites of all walks of life and ages. An independent panel of judges reviewed the submissions and short-listed their top-30 choices. From this short-list, the two winning designs were chosen.