The Lincoln Memorial Reflecting Pool in Washington DC has hardly been out of the news since April, when President Trump vowed to renovate it, and paint it ‘the American flag blue’ by July 4th. Despite the pool being cleaned, cleaned, coated and refilled, within a matter of days the algae that had been troubling for decades returned. To find out why these blooms occur, how difficult they are to deal with, and what Trump might try next, Ian Sample spoke to co-host Madeleine Finlay and Dr. Linda May, a freshwater ecologist at the UK Center for Ecology and Hydrology.
