Winter is when Sereno del Mar turns greenest, the rains soaking the coastal terraces while gray whales pass offshore on their long road south. Emerald Waterworks keeps the grass trimmed and green in this quiet Sonoma Coast enclave, between the cypress windbreaks and the edge of the bluffs. Summer fog rolls in thick off the ocean and leaves the grass beaded with droplets by dawn, so lawns here drink from the sky as much as from the hose. Steady mowing and careful trimming keep that coastal green from going shaggy in the wet months. The name promises emerald, and a clear afternoon above the Pacific shows a cared-for lawn earning the word.