Dig a big hole and fill it with water

I wish it was that easy, get a professional to help. Position, clay content, run off are very important issues, if mismanaged will cost thousands and guarantee grief.

The Dam pictured is well constructed, just under 1 mega litre, it is is part of catchment system and receives a lot of run-off, because this dam never dries up, it has been stocked with 40-50 Silver Perch.