you are absolutely right, that the water usage is an equal issue for coal, oil and other plants. I find it important though to not think in terms of coal vs nuclear, but considering the triangle of options. Forbthe US with its overall low population density water stress might not be an urgent issue. In western Europe it definetely is. For Germany about two thirds of water use are attributable to the energy sector, with the rest being equally divided between industry and households.

Over the last summers multiple plants in western Europe had to drastically lower their output, or in rare cases be shut down. France is discussing to allow for higher river temperatures next to plants, fully aware that this will be the ecological end of the rivers.

As you said there is no nuclear plant on the colorado river. But this raises another issue of water availability. you want the plants to be reasonably close to energy users, so the transportation losses are minimized. And the energy users are also using more water from rivers etc. so you want the plants at already stressed ecosystems.

For the land use of solar, it might be even beneficial as the shading helps to grow crops with less water usage or to protect ecosystems from increases in solar heat.

Due to its size the US has fantastic conditions to transform to renewable energy. The availabe space allows for good integration of renewable plants into the local ecosystems, minimizing their impact. At the same time there will always be wind somewhere in the US in the same wake as their will always be sun somewhere during the day. So with a well connected grid the necessity for base load providers can be reduced better, than in smaller grids.