Los Angeles River
The homeless people were living in every nook and cranny big enough for a tent, tarp or big cardboard box. There are inlets along the banks every hundred feet or so, draining the streets above. They get in and out of the riverbed every day in summer. In winter the river can rage and fill this channel so they must go elsewhere for the winter. Migrating homeless people - imagine that. There are lots of shelters and services for them close by, east of downtown.