The floor of the Lincoln Memorial Reflecting Pool was gray concrete before the renovation, according to reporting that says the gray surface was the former base and that the new coating replaced it with “American Flag Blue.”

What changed

The renovation repainted the drained pool floor from that gray concrete to a deep navy blue.

Why it mattered

Reporters noted that the earlier gray surface tended to collect algae and sometimes gave the water a green appearance, which helped explain why the new color was chosen.

TL;DR

Before the renovation, the Lincoln Memorial Reflecting Pool floor was gray concrete.