The water that was sparkling clear now reflects the dark, threatening sky.

This small lake was mysterious, for its dark waters did not reflect the sunlight.

Also how does this apply when water reflects light & images?

No, the water was not reflecting just plain yellow sky.

He'd always enjoyed the way the water reflected the beautiful sunsets.

In summer the water of the lake reflects like a mirror.

The water reflected the ceiling light but didn't appear to be luminous in its own right.

The still water reflects the blazing color of the trees.

The sun is in my eyes; through green leaves water reflects brightness.

The still water, which looked green in the sunset, reflected the surrounding trees with great clarity.