What did the once ler machine do to the pond?

The Once-ler's machine polluted the pond by releasing toxic waste, which harmed the aquatic life and disrupted the natural ecosystem. This pollution caused the water to become murky and uninhabitable for fish and other creatures, leading to a decline in biodiversity. Ultimately, the damage to the pond reflected the broader environmental consequences of industrialization and greed depicted in Dr. Seuss's "The Lorax."