hello, we are making a concept how to water our community-garden. I wonder if it is possible to collect sufficient water on the site which is rather huge. We have no roof to collect. I read about dams and I did not understand very well: are the dams to collect water freom a creek, form the surrounding site or is it the surface of the site which collects the water? Where can I find technical information on the net about constuction, surface, climate and administrative aspects? You can put fishes and plants in that dam and what do you do when the dam falls dry? I hope getting some information!