Possible, but prohibitively expensive. You can move water downhill easily enough (that’s what rivers are), and you can pipe/pump water throughout a city at acceptable cost. But according to @Oredigger77 in this thread, it costs about 13 cents to move a gallon of water 100 miles. And irrigation quantities are really massive compared to the commodities we shove through cross-country pipelines. According to this, a bushel of corn requires about 3000 gallons of water, which works out to $390 worth of water if you’re pumping it through pipelines just 100 miles long.