Lake's toxin tests extended
PUC examines effects of gun club's shellings.
By Jo Stanley | Staff Writer
Lead contamination tests for Lake Merced are going to be extended,
according to the San Francisco Public Utilities Commission, although
early test results indicate that samples from the bottom of the lake
Published on Monday, November 22, 2004
Lake Merced, which consists of four lakes covering roughlly 250
acres, is intended to be available for drinking water in dire
situations such as eqrthquake or drought -- just as it was during the
late 1800s before Hetch Hetchy was constructed. Scientis are
studyin whether continuing to raise water levesl could cause old lead
shot on the shore to start dissolving.
Lead accumulated for half a century may cause contamination as it washes up from shoreline mud near the Pacific Rod and Gun Club. The gun club, which has been leasing property along 1,500 feet of the South Lake since 1939, stopped using lead shot in the early 1990s. The majority of the residue has either settled into the soil or been covered over by layers of vegetation, clay pigeons or the newer steel shot onshore, according to the PUC.
"We found oxidized lead in the area that was going to be inundated," said Greg Bartow of the PUC. He said off-site testing should be ready by late January.
The good news is that this summer's test results indicate the water samples taken near the lake bottom are safe and the old lead buried in the mud is not leaching into the water. The once-depleted lake has already been raised by some 3 feet in recent years and could go up another 5 feet over the coming decade.
But the still unanswered question is: Would flooding the 1,500-foot shoreline have the unintended consequence of starting to release lead to the environment? If so, it could potentially harm fish and birds as well as pose a hazard for The City's emergency water supply.
For Mondy Lariz, who heads the community-based Lake Merced Task Force and represents a fishing group called California Trout that pushed for the added water, progress so far has been good and this is a time to study how to go further without creating new issues.
"It's kind of a tricky thing," he commented.