Officials hope cold temperatures will kill blue-green algae problem in lakes

TULSA, Okla. (AP) -- Cold temperatures could help ease odor and taste problems in Tulsa's drinking water source, officials said.

Massive quantities of blue-green algae are currently producing record levels of a taste- and order-causing chemical in Lake Spavinaw. Since mid-November, officials have been drawing water from Lake Hudson until the problem subsides.

On Wednesday, the Tulsa Metropolitan Utility Authority was told that the level of geosmin, the taste- and odor-causing chemical, is the highest ever in Spavinaw -- three times the level recorded during the worst episode in 1999.

"If we hadn't gone to Hudson water, today we would be experiencing serious taste and odor in the water," Public Works Director Charles Hardt said. "I mean a serious episode, worse than ever before."

Marsha Slaughter, deputy director of environmental operations, said the geosmin levels in Lake Spavinaw are 1,600 parts per trillion. In 1999, the record high was 590 parts per trillion.

Humans detect taste and odor between 5 and 10 parts per trillion.

A new filter system at Mohawk Water Treatment Plant can effectively treat taste and odor at geosmin levels of 300 parts per trillion with the addition of powder-activated carbon, Slaughter said. It becomes difficult, if impossible, to effectively treat beyond that level, she said.

Lake Spavinaw, which is fed by Lake Eucha, supplies half the city's water customers through the Mohawk Plant; Lake Oologah supplies the other half through A.B. Jewell Water Treatment Plant.

The city also has a contract with the Grand River Dam Authority to draw a limited amount of water from Lake Hudson.

Since 1996, state scientists have linked the abundance of blue-green algae in lakes Eucha and Spavinaw to an overload of nutrients coming from chicken waste that for decades has been applied as fertilizer on pastures throughout the watershed. Taste and odor problems are a result of blue-green algae blooms, which release geosmin.

Slaughter said if the cold temperatures do not slow down the geosmin releases, then the algae may be adapting to the cold.

In a case study by national water experts trying to find treatment solutions, Tulsa has recorded the worst taste and odor problems in the country with water from Spavinaw and Eucha, Slaughter said.