are you planning on having a green house? if so you could put it near where the garden is going to be and put gutters on it to collect any rain or snow run off from that. I would also look into installing a cistern to hold water in your area. that is basically a super sized rain barrel below ground, those can have pumps run off them to pressurize the water kinda like you would for a well. if there are any sheds to put a gutter on and use those roofs to help collect run off water from rain that can be useful also.