The Washington, DC pond has been plagued with algae blooms since 1922.
In 2012, the Obama administration spent approximately $319 million on a renovation, but the problems persisted.
Trump ordered the bottom of the dam to be repainted in "American flag blue" ahead of the United States' 250th anniversary celebrations.
"It will look much more beautiful than it did in 1922 when it was built," Trump said before the repainting, and he hired a contractor who he said was cheaper than the authorities' proposal. The bill ended up at around 131 million kronor.
Despite this, the algae have returned, just days after the renovation was completed. They are now being treated with ozone and hydrogen peroxide, but experts describe the pond as a "perfect" environment for algae growth.
