Wednesday, July 30, 2014
PLACERVILLE, CALIFORNIA
99 CENTS

Lake Tahoe clairity reported improved

By
From page B1 | August 12, 2013 |

While clarity improved at Lake Tahoe for a second straight year in 2012, long-term trends show that climate change is impacting the Lake Tahoe Basin with drier years, less precipitation, higher lake temperatures and projected lower lake levels.

These conclusions are found within the lake’s annual health exam, “Tahoe: State of the Lake Report 2013,” released Aug. 7 by the Tahoe Environmental Research Center at the University of California, Davis.

UC Davis researchers have been continuously monitoring Lake Tahoe’s clarity, physics, chemistry and biology since 1968. This long-term data set helps inform and measure progress toward Tahoe’s restoration goals.

“Every year brings surprises, but with them come new insights,” said Geoffrey Schladow, director of the UC Davis Tahoe Environmental Research Center. “In this last year we saw how nature, combined with the results of the many projects that have been completed in the basin, produced an amazing increase in clarity. The real challenge is to be able to sustain the improvements when nature is working against us.”

The annual average clarity improved by 6.4 feet over the previous year to 75.3 feet. (Clarity data for 2012 was released in February 2013 and is repeated in this report.) This value is within 3 feet of the interim clarity target of 78 feet. The improvement occurred in both summer and winter. The reasons for the improvement include:

• 2012 was a dry year for Lake Tahoe, with precipitation 71 percent of the long-term average. Reduced precipitation resulted in fewer pollutants flowing into the lake.
• The absence of deep mixing. Each winter, surface waters cool and sink downward, mixing with deeper waters. This brings nutrients to the surface, promoting algae growth, while also moving oxygen to deep waters, promoting aquatic life. A lack of deep mixing can contribute to warmer lake temperatures.
• Reduced numbers of tiny Cyclotella algae in 2012. An abundance of the microscopic algae over the past five years has been linked to climate change and coincided with reduced summertime clarity.

Year-to-year fluctuations in lake conditions are normal, which is why TERC researchers note that long-term trends are a better indication of lake health.

Clarity is measured by the depth at which a 10-inch, white Secchi disk remains visible when lowered beneath the water’s surface. When the long-term measurement program began in 1968, the Secchi disk could be seen down to 102.4 feet.

In new research, valuable tools are beginning to provide fresh insights into the processes that drive change in Lake Tahoe. An underwater glider that operated in the lake for 11 days in May 2013 provided the first “snapshots” of water quality across an east-west transect. The data confirmed the presence of giant “internal waves”

deep in the lake that could move algae and pollutants vertically over 150 feet.

Possibly more important was the installation of a water-quality monitoring station in 360 feet of water off the west shore. Connected to shore by an underwater cable, this station provides data from top to bottom every 30 seconds. This is the first such station in any lake worldwide.

Comments

comments

.

News

 
District 2 candidate statements tell of goals

By Dawn Hodson | From Page: A1

Sand Fire nears containment: 66 structures destroyed

By Cole Mayer | From Page: A1 | Gallery

 
Schedule for Highway 50 blasting closures

By News Release | From Page: A3

Tails wagging over dog park approval

By Julie Samrick | From Page: A3

 
Quarter-acre fire in Kelsey

By Rebecca Murphy | From Page: A3

.

Opinion

My Turn: Privatization of public services

By Mark Belden | From Page: A4

 
Policy book

By Mountain Democrat | From Page: A4

 
.

Letters

Piano replaced

By Letters to the Editor | From Page: A5

 
Comments sign-in policy

By Letters to the Editor | From Page: A5, 1 Comment

Save the Guinea Worm

By Letters to the Editor | From Page: A5, 1 Comment

 
Large bangs

By Letters to the Editor | From Page: A5, 2 Comments

Private property gets no respect

By Letters to the Editor | From Page: A5, 1 Comment

 
GDPUD management report

By Letters to the Editor | From Page: A5

District 2 supervisorial special election

By Letters to the Editor | From Page: A5, 3 Comments

 
.

Sports

Ex-Bruin lends a helping hand

By Steven Shaff | From Page: A8 | Gallery

 
Sierra Sharks finish middle of the pack

By Democrat Staff | From Page: A8

Roundup: July 29, 2014

By Democrat Staff | From Page: A8

 
Taz pull through for SSL trophy

By Patty Pope | From Page: A8

.

Prospecting

Nuns discover a pleasant place

By Lexi Boeger | From Page: B1 | Gallery

 
Bargains can be found everywhere

By Democrat Staff | From Page: B2 | Gallery

At a glance: Game time

By Mimi Escabar | From Page: B2

 
Barbecue dinner to benefit Blue Star Moms

By Mount Aukum Winery | From Page: B2

Stagecoach story takes riders on a trip

By Wendy Schultz | From Page: B3

 
Help needed to make cool ties

By Sew 4 | From Page: B3

Stroke and osteoporosis screenings planned

By Life Line Screening | From Page: B3

 
Gold Rush Days activities cancelled this year

By Sacramento Convention And Visitors Center | From Page: B4

Master Food Preservers: Tomato time

By Monique Wilber | From Page: B4

 
Sacramento area museums offer summer fun

By Sacramento Association Of Museums | From Page: B5

 
Build an author platform at the Library

By El Dorado | From Page: B5

.

Essentials

Weather stats 7-29-14

By Michael Raffety | From Page: A2

 
Building permits 6/2-6/2014

By Michael Raffety | From Page: A2Comments are off for this post

Crime Log: July 17

By Cole Mayer | From Page: A2

 
.

Obituaries

Merlyn Wilbur Adams

By Contributor | From Page: A2

 
Lisa Oliver Rose

By Contributor | From Page: A2

Wallace Murrel Thomas

By Contributor | From Page: A2

 
.

Real Estate

.

Comics

.

Women’s Health

Love the skin you’re in

By Noel Stack | From Page: WH4

Dump stress and improve your health, productivity

By Wendy Schultz | From Page: WH7Comments are off for this post

Women’s Health Expo

By Marshall Medical | From Page: WH8

Find the confidence you need to fight back

By Special to the Democrat | From Page: WH12

Our choices directly affect our health

By Special to the Democrat | From Page: WH14

They’re NOT your mother’s hearing devices!

By Marshall Medical | From Page: WH17