Q said watch the water.
According to Lunev, a probable scenario in the event of war would have been poisoning the Potomac River with chemical or biological weapons, "targeting the residents of Washington, D.C."[1] He also considered it "likely" that GRU operatives placed "poison supplies near the tributaries to major US reservoirs."[9] These allegations have been confirmed by former SVR officer Kouzminov [10] who was responsible for transporting pathogens from around the world for Russian program of biological weapons in the 1980s and the beginning of the 1990s. He described a variety of biological warfare acts that would be carried out on the order of the Russian President in the event of hostilities, including poisoning public drinking-water supplies and food processing plants.[11]
Bridge could mean bridging between what he said in his book and today.