Golden Algae

Golden Algae at Lake Mission Viejo

Lake Mission Viejo first experienced a serious loss of our fish population in November 2014 when the aquatic pest algae by the name of “Prymnesium parvum”, never seen before in our lake, appeared. The Golden Algae released its toxin that damaged the gills of fish and compromised their ability to breathe despite good oxygen levels in our lake. Humans and other non-gill-breathers are not affected by the toxin however and affected fish is safe to eat.

Golden Algae, present in Texas and Arizona since the mid-1980s, first appeared in California in the fall of 2013 at East Lake in Yorba Linda. Several other lakes in Southern California were stricken with Golden Algae during early 2014 but LMV initially tested negative. Fish began dying in LMV on November 10, 2014 but when the water was tested again, it was found to have almost undetectable levels of the golden algae. Over the next several weeks almost all of the fish died in LMV beginning with the bass then sunfish, and finally the catfish.

LMVA has reached out to the scientific community, speaking with various researchers and governmental agencies to survey the science, history, and efforts to eradicate Golden Algae from other lakes, ponds, and rivers across the country. The difficult news is that there is no sure treatment available to get rid of this alga. LMVA’s treatments with algaecide targeting Golden Algae have resulted in only some limited and temporary benefits. The golden algae may not go away but may merely stop producing the toxin.

With support from the LMVA board of directors, an expert in the field of harmful algae blooms completed and published this study, the results of which are driving the efforts to decrease the frequency and tocicity to fish of golden algae blooms in Lake Mission Viejo.

LMVA Board and staff are hard at work seeking a solution that will return LMV’s fishery to a stable and healthy state once again and Thank you all for your concern and support as we attempt to solve this stubborn problem.


Day Date Event
Tuesday May 2nd 2023 Blood Drive
Tuesday May 9th 2023 LMVA Board of Directors Meeting
Saturday Jun 3rd 2023 Lake Anniversary Event
Tuesday Jun 13th 2023 LMVA Board of Directors Meeting
Saturday Jun 24th 2023 Boat & watercraft sale


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North Beach (Daily) OPEN 8 AM 11 PM
Membership (Daily) OPEN 8 AM 5 PM
Lake Services (Daily) OPEN 8 AM 5 PM
Boat Rentals – Last rental out at 7 pm OPEN 8 AM 8 PM


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