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Golden Alga in Texas

Archived News Release

April 11, 2003

Lake Whitney Suffering Major Fish Kill From Golden Alga

WHITNEY, Texas — A major outbreak of golden alga on Lake Whitney has killed an estimated 1,750,000 fish. Almost a half million of those died in the last week when the bloom spread to the dam. Texas Parks and Wildlife Department investigators also confirmed the presence of this naturally occurring toxic alga downstream of here along the Brazos River for the first time.

TPWD's Kills and Spills Team reports active golden algal blooms have been affecting fisheries in four major Texas river systems, particularly along the Brazos River, for months. The latest outbreak on Lake Whitney has been devastating, according to Jack Ralph, who heads up the Kills and Spills Team of environmental scientists. "It's a major event right now. We've got in our samples dead stripers up to 44 inches long and catfish up to 46 inches long," he reported. "The bloom was first reported on Feb. 19 and had been languishing in the upper and middle end of Lake Whitney for weeks, but it just started building in concentration and pushing down to the dam where the fish had no escape."

Golden alga has caused significant fish kills during the past few months in Lake Granbury (3.1 million fish) and Possum Kingdom Reservoir (1.65 million fish), but those incidents have tapered off recently, according to agency officials. "The good news is we haven't observed any new fish kills lately on Lake Granbury," Ralph noted. "Also, as the water temperatures rise and the salinity levels decrease, hopefully it will give an advantage to some of the good algae."

Golden alga blooms occur periodically in slightly salty waters of rivers and reservoirs in west and north central Texas. Portions of the Canadian River, the Pecos River, the Colorado River system and the Brazos River system are experiencing impacts from golden alga blooms.

Water samples collected from Lake Waco also confirmed the presence of golden alga, but not in significant concentrations, according to Ralph.

Since 1981, 43 fish kills in Texas have been attributed to golden alga, resulting in the deaths of an estimated 16 million fish valued at more than $5 million. This year's damage along the Brazos River alone has resulted in the deaths of more than 6 million fish. By comparison, a 2001 golden alga outbreak on Possum Kingdom Reservoir, Lake Granbury and Lake Whitney resulted in a loss of 600,000 fish valued at $650,000.

TPWD has investigated golden alga incidents on 13 lakes this year, including: Colorado City, E.V. Spence, Granbury, Moss Creek, Possum Kingdom, Red Bluff, Baylor, Buffalo Springs, Diversion, Sweetwater, Kemp, O.H. Ivie and Whitney.

Although a majority of the fish affected are small baitfish, such as threadfin shad, whose populations can be recover quickly, according to TPWD inland fisheries division director Phil Durocher, the loss of larger game fish can be staggering. "Since we have no cure for this toxin, all we can do is look at mitigation and that means restocking fish and taking protective measures through fishing regulations," he explained. "This doesn't just affect a fishery, it also affects the quality of life for folks who use these lakes for recreation and to make a living. We're going to give these affected lakes top priority."

The species of golden alga that is affecting Texas is Prymnesium parvum. This alga releases a toxin that kills gill-breathing organisms such as fish and clams. According to the Texas Department of Health, anecdotal evidence has shown no human health risks associated with golden alga. Livestock have been observed drinking from rivers during active golden alga blooms without apparent harm.

Golden algal blooms turn the water yellow, gold or a dark tea color. Although no one knows what causes golden alga to bloom, researchers know that conditions that make water salty like drought, brine contamination from oil and gas production, intensive water use and some irrigation practices might contribute to the conditions necessary for blooms.

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Aditional Information:

Would you like to know more?
The Biology of Golden Alga summarizes what we know about the alga and its toxins.

Where does golden alga fit compared to other single-celled organisms?
The Golden Alga Family Tree gives examples of and information about golden alga and other protists.

What does golden alga look like?
TPWD Golden Alga Images has photos of fish kills, golden algal cells, and short videos of live golden alga. These images may be used for noncommercial/educational purposes as long as TPWD is given credit and other site policies are followed.

Golden Alga Information Card: TPWD has collaborated with the Texas Commission on Environmental Quality and other entities to produce a golden alga information card. Download a PDF from the TCEQ website or request a free hard copy from TPWD at

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