Evening walk with Katie, heading upriver: southwest wind, very small alto, maybe some cirrus. It’s been a mid-to-high-20-degree day. Two dolphins head upriver over the sandbar. There are terns and seagulls, and many flowering native grasses—mostly tall feather-grass. And it’s one of those days where it’s easy to see, in the middle of the river, a snaking line of intersecting surface layers, at the corner by the yacht club, on the incoming tide.