Golden algae are documented in Arizona
Apr 15, 2005

Golden algae were confirmed in Arizona waters recently and while these microscopic organisms present new challenges to managing our state's aquatic resources, they do not pose a health risk to humans.

When there is a golden algae bloom, these tiny organisms can release toxins that affect fish and other aquatic organisms with gills, such as freshwater clams. A bloom occurs when the organisms out-compete other algae and experience a rapid population growth. Little is known about what environmental conditions cause a bloom, but scientists suspect it may be a combination of factors.

The Arizona Game and Fish Department has confirmed that golden algae were responsible for fish kills at Water Ranch Lake in Gilbert this winter. Steps are being taken this week to flush the lake and treat it to remove the algae in this 5-acre urban lake.

Biologists have also confirmed the presence of golden algae in Saguaro Lake in the Salt River system. A recent shad die-off in Saguaro Lake may be linked to golden algae, but there is no indication that the shad die-off had any noticeable effect on the fishing success of anglers at the lake. In fact, most angler reports received by the department indicate good angling success there.

Biologists say that algae blooms of this nature are unpredictable: they are typically localized, but not always. It is still unclear what conditions trigger the blooms, but it may be a wide set of variables. Typically, golden algae have done well in lakes with colder water and higher alkalinity, but biologists say even those two factors seem to change at times.

Biologists also stress that while golden algae have affected fisheries in other states, there is no cause for alarm here. The Arizona Game and Fish Department will continue to closely monitor the situation to determine what effects golden algae will have in Arizona and what options may exist to address it.

Anglers and boaters who see dead or dying fish can help by reporting observations as soon as possible to the Arizona Game and Fish Department at Include the species and sizes of fish affected, approximate numbers of fish observed, and the locations where fish were observed. For your safety, please do not touch, collect, or eat dead or dying fish.

To prevent transporting the alga to other waters, drain all bilge areas and live wells of your boat before leaving the lake.

Click here for a list of frequently asked questions about golden algae.