A business tied to a longtime supporter of President Trump was given a no-bid contract to install a water-purification system in the Lincoln Memorial Reflecting Pool earlier this spring. Now that work is coming under scrutiny after algae blooms have come back and turned the iconic pool in Washington a vibrant shade of green rather than the American-flag blue Mr. Trump says he chose. The contract shows that the National Park Service bypassed the competitive-bidding process that is typically required, and gave a $1.7 million contract to the firm, Greenwater Services of Brookfield, Ohio.