I'm going to kick off my contributions to the pathological deltas with a few from volcanic terrains. Due to the rapid production of sediment in their source areas they're commonly youthful and actively growing.
Sparks Lake in the central Oregon Cascades was impounded behind a dam formed when the Quaternary rhyolite domes at the left center of the field of view were emplaced. South Sister (left), Brokentop (right), and Mount Bachelor (out of view) volcanoes supply ample sediment to the streams that drain into Sparks Lake and are rapidly turning this lake into Bachelor Meadow.