According to the latest Bureau of Reclamation runoff and reservoir storage forecast (the “24-month study”, pdf here), combined storage in the two largest Colorado River reservoirs, Mead and Powell, will end this water year up 3.4 million acre feet from last year.
Mead is forecast to end the year up more than five feet in elevation. Powell is forecast to rise 27 feet.
“Water reservoirs created by damming rivers could have significant impacts on the world’s carbon cycle and climate system that aren’t being accounted for, a new study concludes.” https://uwaterloo.ca/news/news/dams-are-major-driver-global-environmental-change “The study, conducted by researchers at the University of Waterloo and the Université libre de Bruxelles, appears in Nature Communications. It found that man-made dam reservoirs trap nearly one-fifth of the organic carbon moving from land to ocean via the world’s rivers.”
See “Global perturbation of organic carbon cycling by river damming” https://www.nature.com/articles/ncomms15347