Seen This Week: The Duckweed Flood

When Panther Hollow Lake overflowed on 20 Aug duckweed floated with it, 21 Aug 2026 (photo by Kate St. John) 23 August 2026 On Thursday 20 August, in 45 minutes from 8:10 and 8:55am, it rained 1.55″ at the Allegheny County Airport. For almost 15 minutes it came down at the rate of 3.4″ per hour. Schenley Park’s Panther Hollow Lake was one of many waterways that overflowed. By Friday morning the flood waters had receded, leaving behind a coating of duckweed right up to the high water mark. Ideally the flood would have been handled by the old concrete overflow channel but it’s blocked by a landslide so the flood ran over the channel edge and down the path to the lake. An old landslide below the Panther Hollow Bridge blocks Panther Hollow Lake overflow channel, 22 Aug 2026 (photo by Kate St. John) Water scoured new ditches and carried an old orange cone into the lake. It also beat down the cattails on its way to the duckweed zone. Flood path to Panther Hollow Lake, 21 Aug 2026 (photo by…