Gold Rush mercury taints area fish; Researcher
says to eat local catches sparingly
GrassValleyUnion
Dave Moller
March 3, 2005
http://www.theunion.com/article/20050303/NEWS/50303001
[distbributed by California Water News]
A federal research chemist says mercury left in Sierra watersheds
by Gold Rush miners could take hundreds of years to flush out naturally.
At a recent meeting of the Bear River Watershed Group, Charlie Alpers
said the water is safe to drink in Nevada and Placer counties, but
as the mercury moves through the food chain, it becomes the toxin methylmercury
and is found in fish.
Consuming too many of those fish could cause neurological problems
in people, Alpers said. His advice was to eat no more than one meal
a week of fish caught in the Yuba, Bear and Deer Creek watersheds.
Alpers and his colleagues at the U.S. Geological Survey have been studying
area watersheds for mercury since 1998. Their work led to a 2003 state
warning to consume no more than four meals of fish per month from the
local watersheds.
"It's probably something you don't want to do every day," Alpers
said about eating locally caught fish.
The USGS studies have found extreme mercury levels at Camp Far West
Reservoir, which straddles the Nevada, Yuba and Placer county lines
above Wheatland. The Nevada Irrigation District's Combie Reservoir
below Lake of the Pines "came in a close second" and needs
follow-up study, Alpers said.
Rollins Reservoir off Highway 174 had mercury levels that were "quite
a bit lower," Alpers said. The cooler temperatures in the lake
may be the reason, he said.
A new Bear River watershed study that is tracing levels of mercury
toxins in the food chain will come out shortly, Alpers told a Higgins
Community Center audience on Tuesday night. Readings have been taken
from plankton, insects, slugs and fish for that study.
Sampling sites have included spots along Camp Far West, Combie, Rollins
and the Dutch Flat reservoirs. Stream samplings have been taken on
Greenhorn Creek in the You Bet Road area.
Alpers said the studies have come to several conclusions.
• "Mercury contamination is pervasive in gold mining areas" with
more coming from placer than hard rock mines. He estimated that through
the years, almost 13 million pounds of mercury were left in the Sierra
by gold miners.
• Only 1 percent of the mercury left behind has turned into the
toxic methylmercury. If that figure was 10 percent, the danger of consuming
fish would rise dramatically.
• Contaminated sediments in foothill lakes and flood plains are
likely to be long-term sources of mercury to the environment "so
the benefits of cleaning up mine sites by be a long time coming."
Back to Awakening the Bear
