Page 28 - ARUBA TODAY

A28 SCIENCE
Monday 27 May 2019
Lake Tahoe’s famed water gets clearer after all-time low

By SCOTT SONNER previous five-year average.
Associated Press Clarity was best when it first
RENO, Nev. (AP) — The clar- was recorded in 1968, with
ity of Lake Tahoe’s cobalt an average depth of 102.4
blue water improved last feet (31.2 meters). The disc
year from its worst level in used to measure it typically
a half-century after weath- was visible at depths of 85
er and runoff returned to feet (30 meters) or deeper
more normal conditions at through the 1970s and hov-
the alpine lake straddling ered near the worst levels
the California-Nevada line. during a severe drought in
A dinner plate-sized disc the late 1990s.
used to measure clarity Since then, efforts have
was visible at an average been underway to re-
depth of 70.9 feet (21.6 store natural wetlands and
meters) in 2018, scientists at meadows displaced by
the University of California, past development. Those
Davis, Tahoe Environmen- areas play an important
tal Research Center said role in filtering water before
Thursday. it enters the lake, Schladow
That’s an improvement of said. “Seasonal weather
10.5 feet (3.2 meters) from extremes will most likely
2017 when a winter with drive greater swings in clar-
unusually heavy snow fol- This April 12, 2012, file photo, shows the clarity of Lake Tahoe, Nev. The clarity of Lake Tahoe’s ity from year to year in the
lowed years of drought, cobalt blue water improved last year from its worst level in a half-century as weather and runoff future, so it’s imperative we
sending sediment into the returned to more normal conditions. continue to invest in the
scenic lake known for its Associated Press lake’s restoration to com-
pine tree-lined beaches and erosion that sends storing critical habitat and ment is in line with the bat new and emerging
and ski resorts. The research sediment particles into the improving our urban areas five-year average of 70.3 threats,” said Joanne Mar-
center typically releases its water, he said. to keep pollution from en- feet (21.4 meters) — an im- chetta, executive director
annual clarity findings in “In 2018, Lake Tahoe’s clar- tering our lake.” provement of nearly a foot of the Tahoe Regional Plan-
the spring after analyzing ity regained the expected The new clarity measure- (30 centimeters) from the ning Agency.q
the data it gathers each seasonal patterns that
month in the previous year. were disrupted by the ex-
Scientists hope efforts to treme conditions of the U.S. forecasters: Expect near normal
combat threats to clar- previous year,” Schladow
ity posed by development said. Atlantic hurricane season
and climate change will Scientists took 26 individual
eventually return Lake Ta- depth readings in 2018, in-
hoe to its historical clear cluding one in March that rectly killed 38 people and
depth of 100 feet (30.5 me- exceeded 100 feet (30.5 caused $49 billion in dam-
ters). meters) of clarity. The worst ages. The Atlantic basin
Dozens of public and pri- readings typically are in the averages 12 named storms
vate partners have been summer, and the best are a year, with six becoming
working to reduce storm- in fall and winter. hurricanes and three be-
water pollution from A reading of 59.7 feet (18 coming major storms.
roads and urban areas meters) in 2017 was the NOAA said there’s a 40%
and restore streams and worst in the 51 years Ta- chance of a normal sea-
floodplains to reduce the hoe’s clarity has officially son, with 30% chances of
amount of fine particles been recorded. The sec- both stronger and weaker
and nutrients that can ond worst was 64.1 feet (20 seasons. “That’s still a lot
cloud the lake, research meters) in 1997. This Sept. 11, 2018 enhanced satellite image made available by of activity,” said NOAA
center director Geoffrey “We are thrilled to see Lake NOAA shows Tropical Storm Florence, upper left, in the Atlantic forecaster Gerry Bell. “You
Schladow said. Tahoe’s clarity improving Ocean, Tropical Storm Isaac, center, and at right Hurricane need to start to prepare for
Clarity can swing widely from the all-time low of just Helene. Associated Press hurricane season now.”
day to day and year to 60 feet in 2017,” said Dar- Hurricane season tradition-
year due to weather con- cie Goodman Collins, CEO By SETH BORENSTEIN or higher. Acting NOAA ally starts June 1, but this
ditions and the flow from of the League to Save Lake AP Science Writer Administrator Neil Jacobs week subtropical storm
streams that can acceler- Tahoe. “These results en- WASHINGTON (AP) — The said a current El Nino, a Andrea briefly popped up,
ate or slow algae growth courage us to continue re- Atlantic hurricane season periodic natural warming marking the fifth straight
is off to yet another early of the central Pacific that year a named storm came
start, but U.S. weather offi- changes weather world- in May or earlier. (Forecast-
cials say it should be a near wide, suppresses hurricane ers name storms with maxi-
normal year. activity in the Atlantic. But mum sustained winds of at
The National Oceanic and other forces, including least 39 mph, or 63 kph.)
Atmospheric Administra- warmer-than-normal sea- Bell said this year’s forecast
tion on Thursday predicted water, counter that. had “competing factors”
nine to 15 named storms. It Last year had 15 named that balanced out. The El
says four to eight of them storms, eight hurricanes Nino brings wind changes
will become hurricanes and two major ones, Flor- that can keep storms from
and two to four of those ence and Michael . Those forming and reduce their
would become major hur- two big storms hit the Unit- strength, but this year’s El
ricanes with 111 mph winds ed States and together di- Nino is weak, Bell said. q