The Lincoln Memorial Reflecting Pool in Washington, D.C. has turned an unusual green color, drawing public attention after recent renovations. Scientists cited in multiple reports say the discoloration is consistent with a bloom of cyanobacteria, commonly referred to as blue-green algae. They describe cyanobacteria as bacteria that can thrive when conditions favor growth, including warm temperatures, ample sunlight, and nutrient-rich water. One outlet notes that the Reflecting Pool’s dark basin can help retain heat, further supporting bloom development. The reports also emphasize that cyanobacteria blooms are part of a broader, growing environmental water threat. Such blooms can produce toxins that pose risks to people, pets, and wildlife, and they can affect ecosystems beyond the immediate site. Scientists also warn that harmful algal blooms can contaminate or threaten drinking-water sources, highlighting concerns for freshwater resource management. While public attention has included criticism and debate, the scientific focus in the coverage centers on how heat, light, and nutrients contribute to cyanobacteria growth and the potential health and environmental impacts if blooms spread or intensify.