Donald Trump on Saturday announced that federal authorities had made “multiple arrests” of people he said were vandalizing the Reflecting Pool as he struggled to explain why the $14-million-plus rehabilitation project he launched for the nation’s 250th anniversary seemingly backfired.

Trump said his predecessors had let the pool turn an algae-stained green and that he’d line it with “American flag blue” so it better reflected the Washington Monument. But after the new pool was unveiled, its blue tinge quickly became a familiar green. Workers treated it with chemicals to kill the algae, but then the painted blue lining on the bottom began to peel.