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Posts Tagged: water

California Agriculture focuses on water efficiency

New UC research shows recycled water is suitable for Napa vineyards, but adds chloride to Salinas Valley soil.

Last year was California's driest on record, and we are now in our third straight year of drought. Growers have fallowed fields they can't irrigate, ranchers have sold cattle they can't feed, and the state wants cities to cut water use by 20 percent. The July–September 2014 issue of California Agriculture presents a special collection of original University of California research on water efficiency.

"This drought is unprecedented — we've never had such a lack of rainfall since we started keeping track," says Doug Parker, who directs UC ANR's California Institute for Water Resources and also leads UC ANR's Strategic Initiative on Water Quality, Quantity and Security. "Farmers are looking for ways they can stretch their water budget."

One way is irrigating vineyards with recycled wastewater from municipal waste treatment plants. California recycles only 7 percent of the 9 million acre-feet of urban wastewater produced per year, and the state wants to nearly quadruple that by 2030. Besides providing a source of irrigation water during drought, recycling water is cost-effective and reduces wastewater discharge to rivers.

To see if recycled water is suitable for use in Napa vineyards, UC Cooperative Extension researchers evaluated the quality of water treated by the Napa Sanitation District (NSD) as well as its impact on soil. They found that the quality of the recycled water was similar to that of other local sources of irrigation water. Additionally, in a vineyard that was irrigated with recycled water for 8 years, the soil did not accumulate salts or toxic ions, such as boron.

"Our work suggests that treated wastewater from the NSD is suitable for irrigation of vineyards over the long term," the researchers say.

One caveat is that the recycled water was relatively high in nitrogen. The higher soil nitrogen levels will be fine for many vineyards but, when needed, growers can easily reduce nitrogen by planting cover crops such as cereals and other grasses during the winter. 


Also in this issue:

Recycled water increases chloride in Salinas Valley soil

Most growers in the northern Salinas Valley have irrigated their crops with recycled wastewater since 1998, raising concerns about salt accumulation in the soil. New research shows that since the year 2000, only a small amount of sodium has accumulated in the 12-inch deep rooting zone. In half of the fields studied, chloride has accumulated to levels that could affect yields of strawberry plants and leafy greens such as spinach. This chloride buildup may be due to the recent lack of winter rainfall, which normally washes salts out of the root zone, and could be mitigated by improving drainage and avoiding soil amendments that contain chloride.

Reducing runoff from alfalfa fields

Accounting for nearly 20 percent of total agricultural water use statewide, alfalfa is California's thirstiest crop — large amounts of irrigation water can be wasted as runoff. New UC research shows that alfalfa growers can reduce this runoff to a comparative trickle by using a mathematical model that predicts the advance of irrigation water across a field in combination with wireless sensors that track the water's advance. This new approach also frees growers from checking the irrigation status of fields in person, saving time and labor.

Predicting which plants will invade California

Most ornamental plants are happy to stay in gardens, but some jump the fence, invading wildlands and crowding out native plants. California has a wealth of native plants, about 3,400 species, but is also plagued by more than 1,500 species of invasive plants, many of which were introduced by the horticultural trade. New UC research identifies 186 ornamentals that have invaded Mediterranean areas in other parts of the world, and so are at high risk of becoming invasive here too. This work could help focus further risk assessments of imported ornamentals, as well as help land managers identify which species to watch for in wildlands.

The entire July-September 2014 issue can be downloaded at

California Agriculture is the University of California's peer-reviewed journal of research in agricultural, human and natural resources. For a free subscription, go to or write to

Posted on Monday, July 21, 2014 at 8:33 AM
  • Author: Debbie Thompson

California's groundwater use during drought threatens future supply

“A significant number of regions in California won't have groundwater available in another generation or two if we continue business as usual.” -- UC scientists Thomas Harter and Helen Dahlke

During the drought, California is pumping from wells. UC scientists make recommendations to manage groundwater.
Nearly two-thirds of the state's water supply is currently being pumped from wells that are tapping into California aquifers.

In the special edition of California Agriculture released today (July 16), UC Cooperative Extension specialist and UC Davis professor Thomas Harter and UC Davis professor Helen Dahlke call attention to the stress being placed on California's aquifers as well as the catastrophic consequences of not having this hidden resource available in future droughts.

In the University of California's premiere journal for agricultural research, the groundwater experts make the following key recommendations:

  • Groundwater is most effectively managed at the local or regional basin level, with support from the state.
  • Local groundwater management entities must be given better tools, such as clear mandates to assess, measure, monitor and allocate their groundwater and control its extraction.
  • The definition of groundwater sustainability can be set at the state level and translated into specific actionable thresholds that must be enforced locally, with a credible threat of state enforcement should the local efforts be unsuccessful.
  • Much better data collection, analysis, reporting and data integration are needed to provide transparency, to support local management efforts and to properly inform the public. This requires much stronger planning and support within the DWR and SWB.

“Fundamentally, even more needs to be done," Harter and Dahlke write. "Local land-use decisions on urban and agricultural development, which have critical impacts on groundwater resources, must be consistent with groundwater management objectives. This will require significant communication between land-use and groundwater managers. Effective integration with water quality management and surface water management efforts, which are governed separately, is also required. And none of these efforts can occur without sustained funding through a mix of local and state sources.”

In their outlook article, Harter and Dahlke also explore one of the most promising ideas to protect our aquifers: groundwater banking.

The idea is that during storms or flood control releases, excess surface water could be directed from streams via existing water conveyance systems onto dormant or fallow agricultural fields, which would then serve as infiltration basins. Solutions need to be developed to add significant recharge to California's aquifers, often during relatively short periods when excess surface water is available. 

A 3-year project, funded by UC Division of Agriculture and Natural Resources, aims to look at the feasibility of such groundwater recharge activities by setting up pilot groundwater recharge field experiments, which would provide valuable data to address concerns about the costs and risks to crops, the influence these projects may have on groundwater levels and flows, and the possibility of recharging contaminated water or degrading groundwater quality by leaching contaminants such as nitrate from the vadose zone. Data collected could serve as a foundation for developing economic incentives at the local, state or federal level to acknowledge the landowner's service to the local community and California's water supply reliability.

To read their entire article, "Out of sight but not out of mind: California refocuses on groundwater,” and the special "Water efficiency" edition of California Agriculture, visit and


Further reading:

UC Cooperative Extension Groundwater Program

Helen Dahlke's groundwater banking project

California Water Action Plan: Improving Groundwater Management (links to state policy and emerging legislation)

California Department of Water Resources report to the Governor's Drought Task Force

California Water Plan Update 2013

Association of California Water Agencies Recommendations for Achieving Groundwater Sustainability

Posted on Wednesday, July 16, 2014 at 10:51 AM

Honey Bees Need Water, Too!

These triple-digit temperatures make us all thirst for water.

Honey bees need water, too.

If you see them taking a sip from your birdbath or taking a dip in your pool, the "sip" means they're collecting water for their hive, and the "dip" could mean they're dying, says retired Extension apiculturist Eric Mussen of the UC Davis Department of Entomology and Nematology.

"Like most other animals, the bodies of honey bees are mostly water," he points out. "Thus, they need to drink water routinely as we do.  Additionally, water (or sometimes nectar) is critical for diluting the gelatinous food secreted from the head glands of nurse bees, so that the queen, developing larvae, drones, and worker bees can swallow the food.  They use water to keep the brood nest area at the proper relative humidity, especially when it gets hot and dry outside the hive.  Water droplets, placed within the brood nest area, are evaporated by fanning worker bees and that cools (air conditions) the brood nest area to keep the eggs and developing brood at the critical 94 degrees Fahrenheit required for proper development."

On extremely dry, hot days, all bee foraging except for water will cease, Mussen says. "Under those conditions it has been estimated that the bees may be bringing back nearly a gallon of water a day."

Unlike us, honey bees cannot simply turn on a faucet. "They will fly up to nearly five miles to find a suitable watering source," Mussen says. "Suitable to honey bees might not be suitable to us, but if it is moist, it may be visited.  Suitable to the neighbors is a separate question.  Honey bees can become quite a nuisance if they visit drippy irrigation lines or hose connections, birdbaths, pet water dishes, swimming pools, fountains, or wet laundry and the like. The water foragers become habituated to those sites.  If you try to dissuade the bees by drying up the source for a while, it becomes evident that the bees will visit the site every so often so they'll be around quickly after the water is returned."What to do? "People have tried to use repellents in the water, but the bees are likely to use the odor as an attractant when attempting to relocate the water source," Mussen points out.  "Some people have had success keeping bees and wasps out of their swimming pools with very lightweight oils or monomolecular films--their purpose is to prevent mosquitoes from being able to breathe.  But, if the water is splashed very much, you'll require a new layer."

And all those bees struggling in your swimming pool? "Not all moribund honey bees in a swimming pool are there because they were trying to get a drink. Every day, approximately 1,000 old honey bees from each colony die naturally.  This normally occurs during foraging, and the bees just flutter down to the ground, sidewalk, driveway, parking lot, or whatever they were passing over.  Some flutter into swimming pools.  They are not dead, yet, so they can and do inflict stings on people who bump into them on the surface of the water. "

Beekeepers should make sure there's a watering source on their property so the bees won't hunt for water elsewhere, Musssen says. It should be available all year around. "Once the bees are habituated to the site, most of them will use that source."

One good thing to know: Bees don't like to get their feet wet. In the Garvey birdbath, we have floating wine corks just for the bees. They can land on a cork to sip water or simply sip from the edge of the birdbath. Besides wine corks, you can also use a stone, a twig or a flat chunk of cork. The Melissa Garden, a privately owned garden in Healdsburg that was designed by internationally distinguished bee garden designer Kate Frey of Hopland, includes a flat floating cork in a fountain. On any given day, you'll see bees claiming it as their own.

Honey bees find water where they can. (Photo by Kathy Keatley Garvey)
Honey bees find water where they can. (Photo by Kathy Keatley Garvey)

Honey bees find water where they can. (Photo by Kathy Keatley Garvey)

A flat floating cork in the fountain of The Melissa Garden, Healdsburg, is great for bees to buzz down and safely take a sip. (Photo by Kathy Keatley Garvey)
A flat floating cork in the fountain of The Melissa Garden, Healdsburg, is great for bees to buzz down and safely take a sip. (Photo by Kathy Keatley Garvey)

A flat floating cork in the fountain of The Melissa Garden, Healdsburg, is great for bees to buzz down and safely take a sip. (Photo by Kathy Keatley Garvey)

Posted on Tuesday, July 8, 2014 at 10:33 PM

How are you conserving water?

People, animals and plants all need water to survive, yet we have less than 1 percent of the earth's water available for our use. And our water supply is diminishing. This year's record California drought conditions mean that now, more than ever, every drop counts.

The average household uses 30 percent of its water outdoors for landscaping and gardening. Inside the home, the majority is used in the bathroom. Just shortening your daily shower by a minute or two can save as much as 700 gallons of water every month!

Pool your knowledge

On May 8, 2014, we're asking you to tell us what you are doing to conserve water. Have you started to take shorter showers? Invested in low-flow faucets and toilets? Let your grass go brown or swapped it for drought-tolerant landscaping? If you're a farmer, do you use new, higher-efficiency irrigation technology?

Maybe you already are conserving water; maybe you aren't. Either way, we want to know about it—and remember, in a survey like this there's no wrong answer. Your answers will help create a clearer picture of what all of us are doing—and can do—to protect our water resources.

Build a more secure future for you and your community in five simple steps:

STEP 1: On May 8, 2014, go online and visit the map at Click on the picture of the map on the right.

STEP 2: Enter your ZIP Code or zoom to your current location on the map.

STEP 3: Click on your location.

STEP 4: Use the online checklist to select all of the ways you are conserving water in your home, garden, landscape, or on your farm.

STEP 5: Attach a photo showing how you're conserving water!

On May 8, 2014, get out there and be a scientist. Tell us where food is grown in your community. Your answers will help build a healthier future for your community, and for the state.

Other ways to join the fun:

  • Are you a teacher? Educator? Parent? Youth group leader? Download our lesson plans and activities from our food activity box. 
  • Pledge a tweet or Facebook status. Join our Thunderclap campaign and donate a tweet or a Facebook status to #BeAScientist on May 8.
  • Join the online conversation by following #BeAScientist on FacebookTwitter and Instagram
  • Learn more about this project by reading our Fact Sheet.


Posted on Wednesday, May 7, 2014 at 9:50 AM
Tags: #BeAScientist (1), conserve (1), drought (10), May 8 (1), water (65)

Drought or Not, Bees Need Water

Honey bees drinking at the Haven's custom watering stations.  Notice that the girls don't stand in water while they drink.

Many insects can obtain the water they need from their food. Bees, however, need to drink water. Honey bees use water to make honey and to cool the hive. As the weather heats up, I thought I'd review some ways to provide water for bees in the garden. This is especially important in this drought...

Posted on Monday, April 28, 2014 at 12:01 PM
Tags: drought (10), honey (1), honey bees (5), water (65)

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