If you haven’t brushed up on your geography lately, a watershed is an area where runoff collects into streams that drain into a river basin or particular body of water. In this example of an urban watershed, it occurs in a corner of the parking structure under the stairs. The urine runoff from the walls, and dark corner, collect into streams that drain into a big barf basin that is replenished by people who drink too much alcohol, or people having withdrawals, or people walking by who puke from the rancid smell of the urine streams. I’ve read that urban watersheds such as this have become much more common in urban landscapes across the country.