Nearly three centuries ago, mission builders dug acequias to carry the San Antonio River out to thirsty fields, and the Espada Aqueduct still lifts water over a creek on the city's south side. A&W Irrigation Service picks up that same old conversation between this city and its water, only now the channels run underground and the gates are sprinkler valves. When a July noon bleaches the sky white and heat shimmers off every driveway, a zone that sputters or a head that floods the sidewalk shows itself fast. Irrigation service and repair, along with lawn care, put the water on the grass instead of the concrete. A lawn that keeps its color through a San Antonio summer is a small modern acequia, still flowing.