An outbreak of blue-green algae will keep Diamond Valley Lake closed until at least Friday, July 6. The algal bloom has turned the water green and is releasing cyanotoxins, which in high concentrations can be harmful to humans and animals, especially when ingested. “Cyanotoxin levels continue to improve, however in part of the lake they remain above levels we would like to see to reopen the lake to recreation,” Metropolitan Water District spokeswoman Rebecca Kimitch wrote in a message Tuesday, July 3.