Sunday, April 26, 2015
YOLO COUNTY NEWS
99 CENTS

Lake Tahoe clarity is best in 10 years

By
From page A1 | February 28, 2013 |

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

Clarity readings since 2000

2012: 75.3 feet (22.9 meters)
2011: 68.9 feet (21 meters)
2010: 64.4 feet (19.6 meters)
2009: 68.1 feet (20.8 meters)
2008: 69.6 feet (21.2 meters)
2007: 70.1 feet (21.4 meters)
2006: 67.7 feet (20.6 meters)
2005: 72.4 feet (22.1 meters)
2004: 73.6 feet (22.4 meters)
2003: 71 feet (21.6 meters)
2002: 78 feet (23.8 meters)
2001: 73.6 meters (22.4 meters)
2000: 67.3 feet (20.5 meters)

Lake Tahoe’s clarity improved in 2012 for the second year in a row, and its waters were the clearest in 10 years, according to scientists who study the lake.

Last year’s average annual clarity level was 75.3 feet, or a 6.4-foot improvement from 2011, according to data released Wednesday by the UC Davis Tahoe Environmental Research Center and the Tahoe Regional Planning Agency.

The lake’s 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 since 1968, when the Secchi disk could be seen down to an average of 102.4 feet.

The annual clarity level is the average of 22 individual readings taken throughout the year. The highest individual value recorded in 2012 was 107 feet, and the lowest was 57 feet.

Researchers provided measurements for last year’s winter (December-March) and summer (June-September) months. Winter clarity last year continued a long-term pattern of improvement, with the best clarity since 1996. The winter average of 88.3 feet in 2012 was well above the worst point seen in 1997 and a combined 12-foot improvement for the past two years.

At 64.4 feet, summer clarity improved 13 feet from the 2011 value, but researchers say the persistent trend is still one of declining summer clarity.

“The improvement we see in both the summer and winter clarity during 2012 is very encouraging,” said Geoffrey Schladow, director of the UCD center. “The lake will continue to be subjected to a range of disturbances, each of which has the potential to impact clarity. There is now growing belief that managing for clarity is possible.”

The rate of decline for average annual clarity in the past decade has been better than in recent decades. In 1997-98, annual clarity reached an all-time average low of 65.1 feet. This year’s value is an improvement of more than 10 feet on that period, but still 22 feet short of the clarity restoration target of 97.4 feet set by federal and state regulators.

Urban stormwater runoff has long been a 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, roads and other developed areas into the lake.

Yet, despite wet winters during 2011 and 2012, clarity improved. Researchers say this could indicate that efforts led by the Tahoe Regional Planning Agency, other management agencies, local jurisdictions and private property owners to reduce urban stormwater runoff are having a positive impact. However, the researchers emphasize that they need more data on stormwater to make more definitive conclusions.

The Tahoe Regional Planning Agency is leading a collaborative Environmental Improvement Program that supports achievement of environmental standards at the lake, with clarity being among the most important.

“Average annual clarity is again moving in a positive direction,” said Joanne Marchetta, executive director of the agency. “With passage of the Regional Plan Update that focuses on the Environmental Improvement Program and water quality treatments in town centers where they are most needed, we expect to see this trend continue.”

Added John Reuter, associate director of the UC Davis Tahoe Environmental Research Center, “We are very excited about the results from 2012, especially within the context of the long-term record for annual and winter clarity. It is particularly encouraging to see clarity improve during wet years when the amount of fine sediments and nutrients going into the lake is high.”

— UC Davis News Service

Comments

comments

  • Recent Posts

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

  • .

    News

    Davis team wins world robotics championship

    By Anne Ternus-Bellamy | From Page: A1 | Gallery

     
     
     
    Nepal quake death toll exceeds 1,800

    By The Associated Press | From Page: A2 | Gallery

    Spring storm delivers late rain, snow to Northern California

    By The Associated Press | From Page: A2

     
    At the Pond: Plenty of pleasures in our bioregion

    By Jean Jackman | From Page: A3 | Gallery

    Pioneering organic chef presents her memoir Monday

    By Special to The Enterprise | From Page: A4

     
    Suspect in UCD assault arrested

    By Lauren Keene | From Page: A4

    Dog park marks anniversary with cleanup

    By Special to The Enterprise | From Page: A4

     
    Rail-safety bill passes Senate committee

    By Special to The Enterprise | From Page: A4

    Free Family Bike Clinic set Sunday

    By Enterprise staff | From Page: A4

     
    Watch them in action

    By Julia Ann Easley | From Page: A5

    Stocks rise on tech earnings; Nasdaq adds to record

    By The Associated Press | From Page: A8

     
    Dodd speaks as part of public policy series

    By Special to The Enterprise | From Page: A9

    We did it (together)!

    By Enterprise staff | From Page: A10

     
    $2.72 million judgment ordered against Dollar Tree Stores

    By Special to The Enterprise | From Page: A10

    Fly Fishers to hear about advanced streamer tactics on Tuesday

    By Special to The Enterprise | From Page: A11 | Gallery

     
    Bicycle activist will speak Monday at Hall of Fame

    By Enterprise staff | From Page: A11 | Gallery

    UCD hosts bike auction Saturday, May 2

    By Enterprise staff | From Page: A11 | Gallery

     
    .

    Forum

    Those texts still linger

    By Creators Syndicate | From Page: B6

     
    New ways of giving locally and beyond

    By Marion Franck | From Page: B6

     
    Study questions accuracy of tumor gene mapping

    By The Associated Press | From Page: B6

    Water, water everywhere?

    By Letters to the Editor | From Page: A12

     
    Mayor’s Corner: A spirit of renewal permeates Davis

    By Special to The Enterprise | From Page: A12

    More work to do for a safe Picnic Day

    By Our View | From Page: A12

     
    Tom Meyer cartoon

    By Debbie Davis | From Page: A12

    Poker proceeds help youths

    By Letters to the Editor | From Page: A12

     
    Invest in water of the future

    By Letters to the Editor | From Page: A12

     
    Anaheim, where The Force is with you

    By Sebastian Onate | From Page: A13 | Gallery

    .

    Sports

    Davis gets two baseball wins in two days

    By Spencer Ault | From Page: B1

     
    Grizzlies dominate young Blue Devils on Senior Night

    By Thomas Oide | From Page: B1 | Gallery

    Energy, fan-friendly happenings highlight UCD spring football game

    By Bruce Gallaudet | From Page: B1 | Gallery

     
    Blue Devil golfers capture CAL Invitational title

    By Enterprise staff | From Page: B1

    UCD roundup: Aggies reach water polo semifinals

    By Enterprise staff | From Page: B2

     
    Blue Devil swimmers are up to the challenge

    By Enterprise staff | From Page: B2 | Gallery

    Babich brings the heat as DHS girls stick it to Oak Ridge

    By Enterprise staff | From Page: B12 | Gallery

     
    DHS softball struggles continue against Sheldon

    By Enterprise staff | From Page: B12 | Gallery

    .

    Features

    .

    Arts

    History comes alive in ‘The Sacramento Picture’

    By Derrick Bang | From Page: A1 | Gallery

     
    .

    Business

    Big Italian food, sports bar to fill Little Prague

    By Wendy Weitzel | From Page: A7 | Gallery

     
    Yolo County real estate sales

    By Zoe Juanitas | From Page: A7

    Davis Roots hires new general manager

    By Special to The Enterprise | From Page: A8

     
    Comcast announces speed upgrade

    By Special to The Enterprise | From Page: A8

     
    .

    Obituaries

    Whitney Joy Engler

    By Special to The Enterprise | From Page: A6

     
    Valente Forrest Dolcini

    By Special to The Enterprise | From Page: A6

     
    .

    Comics

    Comics: Sunday, April 26, 2015

    By Creator | From Page: B8