the lake clear?
Clear Lake has never been clear, and never will be: the name is both a
misnomer and a mystery. This shallow, warm body of water is naturally
"eutrophic" (nutrient-rich) and thus supports a great deal of life --
which means lots of fish, lots of birds -- and lots of weeds and algae.
In the words of Yuba College professor Dr. Harry Lyons, "Clear Lake is
an emerald, not a sapphire."
spilling into the lake?
No. Dead masses of cyanobacteria may look and smell like raw sewage, but
they are something else altogether. Although overflows from sanitary waste
pipes during heavy rains have been documented on a number of occasions
these are winter occurrences, and regular testing reveals nothing that
would indicate an ongoing sewage spill.
safe to drink the water?
Not straight from the lake (as if anyone would think of doing that!) Tap
water from public utilities has been treated and is perfectly safe to
drink and use for cooking. Shallow wells near the lakeshore may be impacted
and should be tested if there's any doubt about their safety.
possible health effects from contact with cyanobacteria?
Yes. Close contact can result in a rash, irritated eyes, or respiratory
symptoms; accidental ingestion could lead to nausea or other intestinal
effects. For these reasons the Department of Environmental Health has
issued a warning advising people to avoid swimming, wakeboarding, water-skiing,
or jet-skiing in areas where algal mats or green scum are present. However,
there have been no medically confirmed cases of illness associated with
blue-green algae exposure in Lake County.
algae infested water harm my pet?
It could: pets should not be allowed to swim in areas where algae blooms
are visible, or to drink the water in those areas.
caused the algae bloom?
Many factors seem to have come together to create a perfect storm for
cyanobacteria in 2009, starting with three years of drought. Low water
levels, unusual springtime water clarity, climatic conditions that encouraged
different levels of lake water to mix, exceptionally hot weather in July
-- all played a causative role.
there so many dead fish?
Low oxygen levels cause fish kills every summer, particularly on the South
Shore. By further reducing normal late-summer low-oxygen levels, heavy
algae growth can make the die-off particularly severe.
we get rid of the algal mats?
The best way for lakeshore residents and resort owners to disperse algal
mats seems to be to spray them with strong jets of water, thus breaking
them up and -- very important! -- adding extra oxygen. Several proposals
have been put forward about ways to skim the algae off for removal, with
the possibility of putting this unwelcome organic material to beneficial
use as fertilizer or even as a source of biofuel, but so far none of these
ideas have checked out in reality.
pollution really to blame?
Yes and no. Detrimental human activities have impaired Clear Lake water
quality by increasing levels of both heavy metals (especially mercury)
and nutrients, and the lake is listed by the state water control board
as an impaired water body. There is no question that these forms of pollution
are real, and that they have been linked to cyanobacteria population growth.
A great deal of work needs to be done to return the lake to a healthy
balance. But on the other hand chronic pollution that has existed
for many years cannot explain the drastic algae bloom that occurred this
summer, since the same stresses have been present in previous years when
no significant algal growth was noted. Over the long run, the lake has
been getting cleaner. It is certainly in far better condition than in
the 1950s and 60s, when a combination of septic system seepage and applications
of heavy pesticide sprays in an attempt to control gnats earned Clear
Lake a mention -- as a horrible example! -- in Silent Spring. Banning
DDT, construction of modern sewage treatment facilities, and implementation
of a strong grading ordinance have done a lot to clean things up since
can be done to improve the health of the lake in the future?
Many many things, big and small. To start with the big ones, the Middle
Creek Project will restore 1200 acres of wetlands north of Rodman Slough,
thus restoring natural filtering processes. Cleanup of the Sulphur Bank
Mercury Mine Superfund site will remove (or at least drastically reduce)
what is by far the most significant source of heavy metal pollution into
the lake. Both of these projects need a great deal of money to become
a reality. Increasing sewage system capacity and preventing future spills
is also very important, so it's encouraging to learn that the county is
in the process of constructing a new sewer line to service the section
of the South Shore where so many spills have occurred in recent years.
Continuing monitoring, erosion control, minimizing agricultural runoff,
and streambed restoration are all important prescriptions for a healthy
lake, as are efforts to increase areas of natural vegetation along the
lakeshore. If you are a rimland property owner, plant tules!
I learn more?
Clearlake TMDL ("Total Maximum Daily Load") stakeholder meetings:
contact County Water Resources Engineer Tom
Smythe for details.
a watershed group: more info from Watershed Coordinator Greg
the Clear Lake Nutrient TMDL, Monitoring and Implementation Plan, and
other relevant information posted to the County website
Supervisor Denise Rushing's 2010 commentary,
"What the lake is telling us."
revegetation can help the lake heal itself
to Lake Group home page