Final answer:
Texas, Montana, and Wyoming are the states not part of the Colorado River watershed, although Wyoming is actually within the basin, contrary to the options provided.
Step-by-step explanation:
Among the states listed, Texas, Montana, and Wyoming are not part of the Colorado River watershed. The Colorado River basin includes portions of Arizona, Colorado, California, Nevada, New Mexico, Utah, and Wyoming, so out of these options, Wyoming is actually included in the watershed.
This river is crucial as it supplies water to more than 24 million people and irrigates 2 million acres of land. The Hoover Dam, one of the largest engineering projects in the United States, is a significant part of the water regulation and distribution system for the Colorado River.