There is a large canal near my apartment (officially labeled the "A Canal" by the Klamath Irrigation District). Back in the days when my knee allowed for walking there, I liked seeing what was in the bottom after it was drained* for the winter. Shopping carts were common.

*The irrigation canals are drained in the winter, so we don't have the lovely and picturesque ice skating scenes of The Netherlands. It's often not cold enough for more than a couple of inches of ice. This has always been the case, it's not because of climate change. The local government doesn't want the liability for children who might fall through and drown while trying to sled or skate.