Specially trained hazardous materials crews have begun a dangerous clean-up job at Lake Curry Dam in Napa County, where an alarming amount of mercury leaked earlier this week.
The city of Vallejo, which owns the dam, says a contractor hired to do routine maintenance work near the dam discovered the leak of the highly toxic substance coming from a 92-year-old non-functioning flow meter.
The meter had been leaking mercury onto the valve house floor for an undetermined period of time, the city said.
Lake Curry Dam hasn't been used as a source of drinking water since 1989, and people aren't in danger, according to Fiona Strykers, assistant director with Vallejo Public Works.
But while the city says water samples from the nearby creeek show mercury levels aren't harmful to humans, mercury is present in the water, and the impact to wildlife is not yet known.
Environmentalists and residents along the creek are concerned. The city has stopped the creek's water flow while it works on the problem.
The city said cleanup will take about seven days. The U.S. Environmental Protection Agency will be onsite Monday.
Bay City News contributed to this report.