All recreational activities at Diamond Valley Lake have been suspended indefinitely due to a large bloom of blue-green algae at the bottom of the lake, the Metropolitan Water District of Southern California announced Thursday. Boating, fishing and hiking are just some of the activities suspended around the lake until the district determines it is safe to use again. The algae, called cyanobacteria, sometimes releases harmful cyanotoxins into the water, which in high concentrations can be poisonous when ingested.