Somewhere in May, Petaluma's rain simply stops, and the town faces a long dry run until the autumn storms return. Watersavers Irrigation is an irrigation business serving Petaluma lawns across that stretch, when every drop has to come from a line in the ground rather than a cloud. The hour to see it is before sunrise, when sprinklers tick across sleeping yards and the egrets are already stalking the marsh at Shollenberger Park beside the river. Water that lands where it should — on the roots, not the sidewalk — is the whole point, and a lawn that holds its color without a puddle in the gutter is a modest kind of victory. It is careful work in a town that understands what water is worth by late summer.