The Metropolitan Water District of Southern California has temporarily suspended all recreational activities at Diamond Valley Lake near Hemet because of an algal bloom. The sometimes toxic cyanobacteria also known as blue-green algae has covered the lake, prompting officials to prohibit boating, fishing and hiking until further notice. Experts assured the public that the quality of the district’s treated drinking water has not been affected. “This is a recreation issue, not a drinking water issue,” Metropolitan Water Quality Manager Dr. Mic Stewart said. “We don’t want folks coming into contact with or fishing in this water.”