The Poquonnock River runs quiet through the middle of Groton, and the tide decides what color the marsh grass will be that morning. All seasons lawn service keeps its mowing routes on the streets that lean toward that water, where turf grows thick on salt-sweetened ground and needs a steady hand to stay even. Mowing, string trimming, edging and yard cleanups — plain work, carried out until the lines run true and the clippings are gone rather than scattered. There is a particular satisfaction in the last pass, when a yard reads as one whole thing again and the smell of cut green hangs in the damp air off the cove. Groton lawns hold their color late down here, and the aim is simply to keep every one of them looking like somebody paid attention.