The Powwow River takes its time through Newton, pooling wide above the old dam, and on a still evening the whole pond goes the color of the sky. New England Ponds & Patios LLC keeps the lawns along that water — mowing, trimming, edging, mulching the beds, and cleanups when the season turns over at both ends. Waterside yards grow soft and fast and hold their dew until mid-morning, so timing is half of the work. A clean edge where turf meets patio stone is worth standing back to look at. The frogs start up at dusk, the mowers go on the trailer, and the yard is done.