Memorial Day boaters captured the scene on video as a massive rockfall crashed into the waters of Lake Powell. The dramatic rockslide happened on the Utah side of the lake — the second largest reservoir in the country — where water levels have continued to plunge due to the unrelenting drought conditions gripping much of the West. … Tyler Knudsen, a senior geologist with the Utah Geological Survey, said it’s difficult to say this early whether the Memorial Day rockfall is linked to the ongoing drought, since rockslides can be triggered by several other external factors — including rainfall, earthquakes, and daily temperature fluctuations.