id author title date pages extension mime words sentences flesch summary cache txt en-wikipedia-org-2576 Colorado River - Wikipedia .html text/html 25133 2944 72 Between 85 and 90 percent of the Colorado River's discharge originates in snowmelt, mostly from the Rocky Mountains of Colorado and Wyoming.[60] The three major upper tributaries of the Colorado—the Gunnison, Green, and San Juan—alone deliver almost 9 million acre feet (11 km3) per year to the main stem, mostly from snowmelt.[61] The remaining 10 to 15 percent comes from a variety of sources, principally groundwater base flow and summer monsoon storms.[60] The latter often produces heavy, highly localized floods on lower tributaries of the river, but does not often contribute significant volumes of runoff.[60][62] Most of the annual runoff in the basin occurs with the melting of Rocky Mountains snowpack, which begins in April and peaks during May and June before exhausting in late July or early August.[63] ./cache/en-wikipedia-org-2576.html ./txt/en-wikipedia-org-2576.txt