Science Sign up for the Slatest to get the most insightful analysis, criticism, and advice out there, delivered to your inbox daily. On June 5, workers began refilling the newly renovated Lincoln Memorial Reflecting Pool. By June 15, the water had been taken over by algae. You know the story: The pool got greener and greener. President Donald Trump, who had made the clarity of the Reflecting Pool a cornerstone of his summer plans, got madder and madder.