The bottle-green waters of Lagunitas Creek linger at White House Pool, where the tidal inlet forms a thin elbow of a lagoon that runs parallel to Sir Francis Drake Boulevard and on past town. Languid as a lazy river, the soft turn in the creek lays out a bucolic scene: tall grass, toasted a soft cinnamon by the sun, edges the shore, while blackberry brambles tangle along the steep soil bank above the water. Surrounded…