By GENEVIEVE BOOKWALTER
About 1,000 gallons of raw sewage spilled into Phoenix Lake yesterday morning after the plug popped off a sewer pipe on Phoenix Lake Road.
"We don't know why; that's never happened before," said Tim McCullough, general manager for Tuolumne Utilities District.
The spill occurred on Phoenix Lake Road near Lori Lane. It was reported by a neighbor at 3:30 a.m. TUD officials immediately shut the sewer pipe off and diverted water in Shaws Flat Ditch around the lake to the Sonora treatment plant, McCullough said.
Water from Phoenix Lake usually flows into Shaws Flat Ditch and down to Sonora.
The treatment plant was turned off until the rerouted water arrived.
Water service in Sonora was not affected, McCullough said, because TUD pumped water from its storage tank until diverted water reached the plant.
Crews finished cleaning and disinfecting the site about 8 a.m., McCullough said.
TUD officials notified officials at Tuolumne County Department of Environmental Health, who took samples of the water and sent them off for testing.
Mike McGee, principal environmental health specialist for the county, said results from those tests should be back tomorrow.
"We don't know how bad it was or wasn't," McGee said.
However, he said, heavy snow runoff will probably dilute sewage to safe levels.
However, runoff will also make it difficult for officials to tell what contaminants are from this sewage spill and what is from sources farther upstream.
"There's all kinds of bacteria that comes out of the woods," McGee said. "High bacteria counts in streams and lakes, at this time of year, that's normal."
To decipher where different contaminants originated, environmental health officials took samples both around the lake and along the creeks leading to it.
While he didn't expect a problem, McGee said he won't know the sewage spill's effect on Phoenix Lake water until test results return.
Until then, "it might be the best course of action not to play in it," he said.
Contact Genevieve Bookwalter at firstname.lastname@example.org .