Shark River Hills leans out over its estuary on a low bluff, the streets bending down toward the marina and the marsh grass that turns copper by November. Sienna Landscaping LLC keeps lawns on that slope — salt in the air, wind off the water, grass that grows fast in the damp and needs a steady hand to stay level. When winter crosses the river it comes in wet and heavy, and the plowing starts on the hill streets first, because a driveway on a grade forgives nothing. Scraping a walkway down to bare concrete before anyone's first cup of coffee is a good way to start a cold morning. Then April, and the mowers running again with the halyards ringing at the boats below.