Friday, August 29, 2014
YOLO COUNTY NEWS
99 CENTS

Researchers: Tahoe clarity looks to be stabilizing

TahoeW

The John Le Conte research vessel is used by scientists from the UC Davis Tahoe Environmental Research Center to measure clarity in Lake Tahoe. Kat Kerlin/UC Davis photo

By
From page A1 | March 14, 2014 |

Clarity levels within the iconic blue waters of Lake Tahoe continued a decade-long trend of stabilization in 2013, according to UC Davis scientists who study the lake.

Data released Thursday by UCD’s Tahoe Environmental Research Center and the Tahoe Regional Planning Agency reported the average annual clarity level for 2013 at 70.1 feet.

While the reading represents a 5-foot decrease over the previous year, it is still well above the lowest value recorded in 1997 of 64.1 feet and above recent years’ averages.

The clarity level this year is the average of 25 individual readings taken throughout the year. The highest individual value recorded in 2013 was 90 feet, and the lowest was 49 feet, due to seasonal variations.

Researchers provided measurements for both winter (December-March) and summer (June-September) months. Winter clarity last year continued a long-term pattern of improvement that has been evident since 1997.

The winter average of 77.9 feet in 2013 was well above the worst point seen in 1997, although 10 feet less than in 2012. Large stream inflows in the winter of 2012-13 were mainly responsible for the lower values.

At 63.8 feet, summer clarity was almost identical to the 2012 value (64.4), but the persistent trend is still one of declining summer clarity.

Clarity is measured by the depth at which a 10-inch white disk, called a Secchi disk, remains visible when lowered beneath the water’s surface. The measurements have been taken continuously since 1968, when the Secchi disk could be seen down to 102.4 feet.

Current drought conditions have impacted the Secchi depth record. The last five readings, taken in November and December, showed significantly clearer waters than measurements taken the previous year. Low precipitation means that less clarity-reducing pollutants are brought into the lake.

“Clarity in Lake Tahoe largely reflected what we saw in the weather in 2013,” said Geoffrey Schladow, director of the Tahoe Environmental Research Center. “At the beginning of the year, clarity was lowered by large stream inflows. At the end of the year, the low inflows resulting from the drought conditions helped to improve clarity.”

While the average annual clarity in the past decade has been better than in preceding decades, it is still short of the clarity restoration target of 97.4 feet set by federal and state regulators.

A regional monitoring program for urban stormwater was initiated in the Tahoe basin in 2013. Urban stormwater runoff is believed to be the major contributor to reduced clarity at the lake. Most of that runoff occurs during the winter and spring, when rain and snowmelt carry small, inorganic particles from the land into the lake.

The new program will allow researchers and agencies to better understand the annual variations in lake clarity, and to assess the performance of restoration strategies and practices.

— UC Davis News

Comments

comments

  • Recent Posts

  • Enter your email address to subscribe to this newspaper and receive notifications of new articles by email.

  • .

    News

    Saving Putah Creek: a quiet concert at sunset

    By Elizabeth Case | From Page: A1 | Gallery

     
    Mr. Dolcini goes to Washington

    By Tanya Perez | From Page: A1 | Gallery

    Winton to be feted for her many years of community work

    By Bruce Gallaudet | From Page: A1 | Gallery

     
    Davis Innovation Center team fields questions

    By Dave Ryan | From Page: A1 | Gallery

    Researchers solve mystery of Death Valley’s moving rocks

    By The Associated Press | From Page: A2 | Gallery

     
    California extends review of $25B delta plan

    By The Associated Press | From Page: A2

     
    Assembly approves statewide ban on plastic bags

    By The Associated Press | From Page: A2

    Need a new best friend?

    By Enterprise staff | From Page: A3 | Gallery

     
    Equestrian eventing competition slated

    By Enterprise staff | From Page: A3

    Dinner, auction benefit Yolo County CASA

    By Enterprise staff | From Page: A3

     
    Forum explores local mental health services

    By Enterprise staff | From Page: A3

    Solar-cooking workshop set at Food Co-op

    By Enterprise staff | From Page: A3

     
    Celebrate the Senior Center at Sept. 9 luncheon

    By Enterprise staff | From Page: A3

    Tee off for Davis’ continued prosperity

    By Lily Holmes | From Page: A4

     
    Kids can sign up for a library card and get a free book

    By Special to The Enterprise | From Page: A4

     
    Explorit Science Center: Volunteers supercharge summer camp

    By Lisa Justice | From Page: A4 | Gallery

    Free blood pressure screenings offered

    By Enterprise staff | From Page: A5

     
    Bodega Marine Laboratory hosts open house

    By Special to The Enterprise | From Page: A5 | Gallery

     
    Local group charts a year’s worth of beauty in flowers

    By Enterprise staff | From Page: A5

    Name Droppers: UCD honors two of its own

    By Enterprise staff | From Page: A6

     
    Books, conversation and poetry at Logos

    By Enterprise staff | From Page: A7

     
    .

    Forum

    What if we need MRAP?

    By Letters to the Editor | From Page: C2

     
    How could tank be helpful?

    By Letters to the Editor | From Page: C2

     
    Tom Meyer cartoon

    By Debbie Davis | From Page: C2

    Don’t sentence our police to death

    By Special to The Enterprise | From Page: C2, 1 Comment

     
    Will Davis see river water?

    By Letters to the Editor | From Page: C2

    Let’s sell the MRAP on eBay

    By Letters to the Editor | From Page: C2

     
    Seeing both sides of ‘tank’

    By Letters to the Editor | From Page: C2

    Travel buddy is getting too fat

    By Creators Syndicate | From Page: B5

     
    .

    Sports

    Devils scrimmage with Sac

    By Wayne Tilcock | From Page: B1 | Gallery

     
    UCD-Stanford: the clock is down to counting the minutes

    By Bruce Gallaudet | From Page: B1

    Forget the score; focus on the energy brought by Aggies

    By Bruce Gallaudet | From Page: B1

     
    Returning seniors, new faces lead promising DHS links squad

    By Evan Ream | From Page: B1 | Gallery

    Devil golfers return from Scotland with smiles on their faces

    By Evan Ream | From Page: B1 | Gallery

     
    Wire briefs: Aces cruise past Cats at Raley

    By Wire and staff reports | From Page: B6

    Sports briefs: DHS girls fall by the slimmest of net margins

    By Enterprise staff | From Page: B6 | Gallery

     
    .

    Features

    .

    Arts

    ‘The November Man’: Who can be trusted?

    By Derrick Bang | From Page: A9 | Gallery

     
    B Street’s ‘The Ladies Foursome’ is aces

    By Bev Sykes | From Page: A9 | Gallery

    .

    Business

    Technology makes a great car better

    By Ali Arsham | From Page: C1 | Gallery

     
    .

    Obituaries

    Margarita Elizondo

    By Special to The Enterprise | From Page: A4

     
    Elaine Dracia Greenberg

    By Special to The Enterprise | From Page: A4

    .

    Comics