One of President Donald Trump’s pet beauty projects for Washington was supposed to make the Lincoln Memorial Reflecting Pool look blue, like part of the US flag.

Enter Mother Nature. Algae has proliferated in the water, turning it a swampy green.

“Can you see it in my photos? Oh well, I’ll just use a filter to hide the algae,” said Farrah Lu, a 43-year-old tourist from China.

The invasion comes just days after the completion of the pool repainting project, part of Trump’s drive to put his stamp on Washington with things like a ballroom at the White House and a huge arch by the Potomac River.

Under Trump’s orders, the long, rectangular pool, designed to capture reflections of the Washington Monument on the National Mall, was drained and painted in what he calls “American flag blue”.

This is hallowed Washington real estate: it was from the steps of the Lincoln Memorial that civil rights leader Martin Luther King Jnr gave his famed “I Have a Dream” speech in 1963 to several hundred thousand people gathered below around the pool.