Thursday, July 31, 2014
YOLO COUNTY NEWS
99 CENTS

Ask the expert: Davis’ groundwater future is unknown

By
From page A1 | February 07, 2013 |

* Editor’s note: This is the third in a series of “Ask the expert” columns that will appear in the coming days, in advance of the Measure I election, regarding various technical aspects of the city’s water utility and the proposed Woodland-Davis surface water project.

The expert: Graham Fogg, UC Davis professor of hydrogeology. Fogg’s academic interests include groundwater contaminant transport, groundwater basin characterization and management, geologic/geostatistical characterization of subsurface heterogeneity for improved pollutant transport modeling and numerical modeling of groundwater flow and contaminant transport.

The question: How long can Davis survive with the current well water system and have safe, drinkable water? Can you briefly describe the problems that could arise with the city’s drinking water, in terms of supply and quality, if Davis remained on a well-only system, and when those problems might occur?

The answer: Research indicates that downward movement of contaminated groundwater is a long-term and ongoing process and the deeper groundwater quality potentially will continue to degrade in the coming decades even in the unlikely event that anthropogenic contamination at the surface is eliminated.

In other words, the current well water system, which does include a number of aged wells that need to be replaced, is sufficiently vulnerable to ongoing contamination from surrounding land uses that it would be prudent to consider alternative or supplementary sources of water.

One alternative is to construct more wells in the so-called deep aquifer, which is perhaps more protected from surface contamination because of its depth beneath still more clay and silt layers.

Unfortunately, the capacity of the deep aquifer to satisfy city water demand is unknown at this time because there is not yet enough information on the lateral extent of that aquifer and on how and at what rate it is recharged.

Even if such information becomes available, however, concentrating more groundwater pumpage in the deep aquifer will only accelerate the downward movement of contaminated groundwater toward the deep aquifer. In other words, just because the deep aquifer is deep does not mean it is invulnerable to contamination. When I arrived in Davis in 1989, the intermediate depth aquifer zones that Davis has tapped also were considered invulnerable to contamination. Twenty-four years later it is a different story.

How long can Davis survive with the current well water system? Perhaps one to three decades. Can Davis survive significantly longer if it taps into the deep aquifer? Answer: Unknown, and unlikely to be known until substantially more development of the deep aquifer occurs. The costs of different options must be weighed, but one should also weigh the different degrees of uncertainty inherent to these options.

The main problem with staying on wells likely would be significant uncertainty regarding future capacity of the aquifer system to deliver sufficient volumes of water that meet drinking water standards, both with respect to anthropogenic contaminants (e.g., nitrate and salinity from irrigation) and natural contaminants such as selenium and chrome.

Because the amount of water the aquifer can safely yield is unknown, it is also possible that development of that aquifer will lead to overdraft conditions. In the case of groundwater overdraft, the possible detrimental effects are land subsidence, higher energy costs of pumping from deeper static water levels and intrusion of deep saline groundwater that lies below the deep aquifer.

Comments

comments

Enterprise staff

  • Recent Posts

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

  • .

    News

     
    Local therapists bring ‘Daring Greatly’ movement to Davis

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

     
    Davis area youths learn wilderness survival skills

    By Charlotte Orr | From Page: A1 | Gallery

     
    Crews battle grass fire near Davis

    By Lauren Keene | From Page: A2

    Sorting out the claims after pipe break: Who pays?

    By The Associated Press | From Page: A2

     
    Governor says immigration solution is a priority

    By The Associated Press | From Page: A2

    Firefighters keep Yosemite blaze far from sequoias

    By The Associated Press | From Page: A2

     
    Police nab three for vehicle theft

    By Lauren Keene | From Page: A2

     
    As farmland subsides, aquifer worries mount

    By San Francisco Chronicle | From Page: A3 | Gallery

     
    Pogledich named Yolo County counsel

    By Anne Ternus-Bellamy | From Page: A5 | Gallery

    Tuleyome launches Kickstarter campaign to publish a children’s nature book

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

     
    Davis teen on California team for national horticulture competition

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

    Truth and authenticity on radio program

    By Special to The Enterprise | From Page: A8

     
    Senior sing-along held monthly

    By Enterprise staff | From Page: A8

    .

    Forum

    A rose by any other name

    By Creators Syndicate | From Page: B5

     
    Civilians are innocent victims

    By Letters to the Editor | From Page: A6

    Thanks for your kindnesses

    By Letters to the Editor | From Page: A6

     
    Questions, questions, questions

    By Letters to the Editor | From Page: A6

    Speak out

    By Enterprise staff | From Page: A6

     
    Ross Douthat: Democrat, Republican patterns are changing

    By New York Times News Service | From Page: A6

    Tom Meyer cartoon

    By Debbie Davis | From Page: A6

     
    .

    Sports

    River Cats snap three-game losing streak

    By Enterprise staff | From Page: B1 | Gallery

     
    Davis Water Polo U10 girls are golden

    By Spencer Ault | From Page: B1, 1 Comment

    Aggie Silva mixed school and strikes; wins Reno tourney

    By Bruce Gallaudet | From Page: B1 | Gallery

     
    Lucky No. 7: Giants snap losing streak

    By The Associated Press | From Page: B1

    Davis Rugby teams wrap up summer season

    By Enterprise staff | From Page: B2

     
    DHS tryout schedule updated; physical packets due

    By Enterprise staff | From Page: B2

    49ers WR Brandon Lloyd enjoying return to NFL

    By The Associated Press | From Page: B3

     
    Hammel struggles in A’s loss to Astros

    By The Associated Press | From Page: B8

    .

    Features

    Happy 103rd birthday!

    By Wayne Tilcock | From Page: A2

     
    Fay Libet: 100 years young

    By Spencer Ault | From Page: A3 | Gallery

    Future subscriber: Sonya Theresa Arnold

    By Enterprise staff | From Page: A4

     
    Wedding: Alpers – Halprin Jackson

    By Special to The Enterprise | From Page: A4

    Engagement: Snyder-Oerman

    By Special to The Enterprise | From Page: A4

     
    .

    Arts

    Hot City heats up Winters gazebo

    By Enterprise staff | From Page: A7

     
    Enjoy some Mischief at First Saturday event

    By Enterprise staff | From Page: A7

    British organist to play in Davis

    By Enterprise staff | From Page: A7

     
    Native American dancers to perform in Davis

    By Enterprise staff | From Page: A7

    Winters stages ‘All’s Well That Ends Well’

    By Enterprise staff | From Page: A7

     
    Landscape exhibition returns to Davis

    By Special to The Enterprise | From Page: A7

    Hear live music at Monticello

    By Enterprise staff | From Page: A7

     
    New KDRT show features touring musicians

    By Enterprise staff | From Page: A7

     
    .

    Business

    .

    Obituaries

    .

    Comics

    Comics: Thursday, July 31, 2014

    By Creator | From Page: B6