The algae in the Reflecting Pool was most likely caused by a mix of stagnant water, sunlight, and excess nutrients that let algae bloom quickly. Reports also point to the recent renovation and cleanup efforts possibly contributing to the problem, with experts saying the issue does not appear to have been intentional vandalism.

What likely triggered it

  • Warm, still water creates ideal conditions for algae growth.
  • Nutrients like nitrogen and phosphorus can feed blooms.
  • Sunlight helps algae multiply fast.
  • Recent treatment/repair work may have disrupted the pool’s balance and made the problem worse.

What reporters found

Coverage from multiple outlets says internal records and experts did not support claims that the algae problem was caused by vandals. Instead, the evidence points to environmental and maintenance factors, not deliberate damage.

Why it kept coming back

Once algae starts, it can be hard to stop if the water stays warm and still. Some reporting also notes that efforts to suppress one bloom may have unintentionally helped conditions for another.

TL;DR: The Reflecting Pool algae was most likely caused by ordinary bloom conditions — stagnant, nutrient-rich, sunny water — rather than vandalism.