New Algae Species
Causes Earthy, Musty Taste and Smell in California Drinking
Water
September 26, 2005
Regional water quality experts reported progress today in
dealing with an unrelenting new strain of algae in Lake Skinner
that is affecting the taste and smell of drinking water in San
Diego and southwest Riverside counties.
Jill T. Wicke, manager of water system operations for the
Metropolitan Water District of Southern California, said the
district will apply another treatment of copper sulfate-- the
fourth application since Aug. 8 -- to address the growth of a
persistent new species of blue-green algae in the drinking water
reservoir near Temecula. "We're hoping that we've turned the
corner in dealing with this aggressive new algae strain, which
has been particularly difficult to treat," Wicke said. "Since
the last treatment Sept. 17, we have observed a decline in algae
in the lake, which we expect will continue to decline with
Saturday's application.
"We also expect that cooler fall temperatures will help
reduce algae growth and re-growth. It might, however, take as
long as three weeks before some consumers notice an improvement
in the taste and smell of their drinking water," Wicke said.
Wicke reiterated that water with an earthy-musty taste and smell
continues to be safe to drink, but that consumers with sensitive
noses and palates may find it unpleasant. The earthy-tasting
water, which cannot be corrected in the filtration and treatment
processes, is being supplied by Metropolitan to supplement local
supplies of Eastern and Western municipal water districts based
in Perris and Riverside, respectively, and the San Diego County
Water Authority.
While Saturday's copper sulfate treatment -- the safe and
approved method to control algae growth -- takes effect,
Metropolitan continues to by-pass the lake through nearby
pipelines to isolate the lake's supplies in its distribution
system. Metropolitan ultimately plans to return the lake to
service once the water's aesthetics improve. In the meantime,
consumers noticing an earthy-musty taste and smell in their
drinking water can refrigerate it to improve its aesthetics or
should consider using bottled water, officials said.
Growth of algae in open reservoirs is generally a seasonal
problem that occurs in warm months. As in previous years, the
cause of this year's taste-and-smell episode has been identified
as 2-methylisoborneol (MIB) and geosmin, compounds that are
produced from the growth of certain algae in freshwaters
throughout the world. Typically, MIB and geosmin levels increase
in summer months when the warmer weather accelerates algae
growth.
This year, however, the seasonal issue has been complicated
by the appearance of the new algae species, Planktothrix
perornata, which was first identified in Lake Skinner in late
August, said Dr. Mic Stewart, Metropolitan's water quality
manager. "Unlike other freshwater algae species, which attach to
the sides or bottom of a reservoir, this new strain tends to
proliferate throughout different lake levels, making it much
more difficult to treat because of its widespread occurrence in
the lake," Dr. Stewart said.
Metropolitan officials speculated that the new algae species
might have been imported in supplies from Northern California
following the June 2004 levee break in the Upper Jones Tract
island of the San Francisco Bay/Sacramento-San Joaquin Delta.
Dr. Stewart said that recent reports suggest the new species has
caused similar problems in the northern part of the State Water
Project.
Source: Metropolitan Water District of
Southern California September 26, 2005 |
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