Algae prompts concerns at Lake Mead

Tuesday, Sept. 9, 2003 | 9:38 a.m.

A blue-green algae that can be toxic in high concentrations has been discovered at low levels in the Las Vegas Wash and the Overton Arm of Lake Mead, officials said.

At the levels discovered in the local water samples, there is no threat to the drinking water or to people visiting the lake, officials said.

The algae, cylindrospermosis, was detected by the Southern Nevada Water Authority this summer, said Allen Biaggi, administrator of the Nevada Division of Environmental Protection.

The algae is common in lakes around the world, including the Great Lakes and Florida lakes. It thrives in warm water.

"We've had blue-green blooms before, primarily in Northern Nevada," Biaggi said. "As the temperatures cool in the fall, they die off fairly quickly. What I find interesting is, it is happening all over the lake."

A subcommittee of the Lake Mead Water Quality Forum is recommending that water officials create a management plan for next summer, when Lake Mead's temperatures warm up.

Members of the Lake Mead Water Quality Forum are expected to address the issue at a meeting Thursday.

The water samples indicated 22,000 to 27,000 cells of the algae per milliliter of water, which is above the World Health Organization guideline of 20,000 cells per milliliter.

"It's not serious yet," J.C. Davis, spokesman for the Water Authority, said.

Unless the cells reach 100,000 cells per milliliter or higher, there is no danger to swimmers, boaters or wildlife, Davis said. Southern Nevada's algae has not been tested for toxins, but there have been no reports of illnesses or deaths among the lake's wildlife.

The good news for Southern Nevada residents drinking the water that comes from the lake is that ozonation, the treatment used on the water supply, kills the algae, Davis said.

"There's no immediate cause for concern," National Park Service biologist Kent Turner said. "But potentially, it's something very important for us to continue monitoring."

The fact that the lake's level continues to drop probably encouraged the growth of the algae, Turner said.

The algae, which is not always visible, was found in areas of the lake where other forms of algae have previously been found, Turner said -- mainly near outflows such as the wash.

Blue-green algae are tiny, simple plants that live in fresh or salt water, even damp areas, around the world, according to North Carolina's Public Health Department's website.

No human deaths from blue-green algae have been reported in the United States.

In 1996 in a kidney dialysis clinic in Brazil, 126 patients became ill and 60 of them died from untreated water heavily contaminated with blue-green algae used for dialysis during a water shortage.