Before dams were built, approximately 18,500 million cubic meters (15 million acre-feet) of water flowed down the Colorado River to the Pacific Ocean each year. This year’s pulse flow—the product of an historic agreement called Minute 319—a total of 130 million cubic meters (105,000 acre-feet) of water will be released over an eight-week period. While small in comparison to the natural floods of the past, scientists think it will be enough to trigger some dramatic changes downstream.