A thunder storm rolled in around sunset and produced a few rainbows. Four to be exact. The primary rainbow is easy to see; the secondary takes some squinting. Each rainbow is "reflected" in the water. However a rainbow is not an object and cannot be reflected. The reflected rainbows are generated by light that has passed through different rain drops and has traveled a different path to your eyes. Rather than the direct path to eyes like the sky bow, the light for the lake bows travels from the raindrops to the lake surface, then to your eyes.
The flare in intensity at the bottom of the bow was due to the sun peaking between the clouds, shown below