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Looking for water shortage answers

Well, now — there’s a deep subject.

So goes the old corny joke that may not be quite as amusing these days as more farmers wrestle with how to deliver quality water – and even fertilizer and other chemicals – to their crops as surface deliveries decline.

In California’s vast Westlands Water District alone, millions of dollars have been spent sinking new wells or rehabilitating old ones in just the past couple years as growers seek to keep alive high value permanent crops in the face of diminished water coming to them through the Sacramento-San Joaquin Delta.

On the San Joaquin Valley’s East Side, at the same time, growers like B.J. Hearn of Hanford have watched as water levels continue to drop.

“Thirteen feet in 2008 and 7 feet in 2009,” says Hearn, who grows peaches, grapes and walnuts. “And it’s not going to come back up.”

Those sorts of concerns explain why Hearn was among about 60 people, many of them growers, who attended a workshop on “Water Sources: Wells and Surface Water” at California State University, Fresno.

The program was part of a series that is being presented by the Center for Irrigation Technology with help from the California Department of Water Resources.

Hearn and other growers, like Russ Wilson of Fowler, were looking to learn more about wells – he has three that date from 40 years ago. Wilson was also looking to learn how to better use drip irrigation to apply chemicals to his vineyards where he grows grapes for raisins and wine.

“I can apply chemicals to treat for vine mealybug through a drip system for half what it would cost me to spray them,” Wilson said, adding that he has 20 of 100 acres under drip.

Wilson said he took away some good information from the program. It included a look at well construction, which he said armed him with information he’ll need if he revamps existing wells or drills new ones. And a talk on water quality treatment included warnings on mixing of chemicals that can clog irrigation lines and filtration equipment.

Ken Schmidt, principal with a hydrogeologic consulting firm in Fresno, talked of the machinery used to drill wells and the casing and screens that are part of the system. His specialty is finding new water supplies, and he also characterized himself as “a troubleshooter.”

When it comes to municipal wells, he said, it may be necessary to drill deeper as water levels drop and water quality declines.

“Shallow wells may have nitrates and other constituents not suitable for drinking water,” he said. “That’s less of a concern for agricultural irrigation.”

Problems he has uncovered include the wells that produce too much sand.

Any gravel pack used for filtration should be uniform, clean, well rounded, and contain more than 90 percent silica. A good thickness, he said, is 3 to 6 inches.

Schmidt said it is important to keep good records on drill cuttings and the sites where wells are sunk, particularly when a test hole is done first.

He said it is best to design wells; with efficiency in mind to avoid large drawdowns of water – the difference between the depths of water when it isn’t being pumped and the pumping level when the water is pumped.

Getting water out of the ground or from surface sources is only part of the solution. Knowing its chemistry – and the chemistry of any products that are added – is also vital, especially when drip lines are involved.

Deborah Miller, president and owner of Deerpoint Group Inc. in Fresno, talked of those challenges. Her company’s services include chlorination of irrigation water, a patented program called Clear Water for treatment to prevent plugging and scale buildup; and another program called Blue Water that uses copper sulfate to control algae and certain weeds in reservoirs or canals used for irrigation.

“Limited availability of surface water means people are turning to sources with lower water quality,” Miller said.

She showed a chart that can be used to alert growers to combinations of chemicals – the products they use in fertigation, for example – with other chemicals that can result in compounds not readily useable for plants or in insoluble deposits that can clog drip lines.

“Removal of scale after it forms is never the preferred option,” Miller said, likening the problem to that of clogged arteries in humans. “Is it better to follow a diet to avoid that or to let it build and then perform an angioplasty?”

Scale removal for drip lines, she said, is “usually more expensive than preventive maintenance.”

Natural impurities abound in surface water, and common water quality issues related to irrigation include the hardness of water, alkalinity, pH level, iron and manganese levels, bacteria, algae, and the chemicals used in fertigation.

Algae from surface water can trigger excessive back flushing, which Miller said will not adequately address the problem. She said growers may need to work closely with their water districts to address such issues.

Miller talked of jar tests that growers can conduct before adding products to a drip line.

“But you need to be sure to look at flow rates — how fast will it be added. For example, if you’re going to be adding at 20 gallons a minute and using 1,000 gallons, do the ratio at 2 percent by volume,” she said.

Miller said the solution should sit in the jar “overnight, not for an hour or so.” The idea is to see how the chemicals will precipitate out into the solution.

“Look at the fertilizer label to see the main component, then look at the solubility chart,” she said.

“If there is any haze at all, consult your fertilizer company, your water treatment company or the university,” Miller said.

Bill Green, education manager for the Center for Irrigation Technology, talked of the center’s Agricultural Pumping Efficiency Program, which conducts efficiency tests subsidized by Pacific Gas and Electric Co.

“It takes energy to move water, and this is about saving energy,” Green said.

He cited a well rehabilitation project in Selma that cost $2,702, but paid for itself within a year, resulting in a much more efficient pumping system and a reduction in the kilowatt hours per acre foot by nearly one half.

To evaluate wells, Green suggests comparing them to other wells in the area, gathering historical data on the well or pump and any testing and doing a video camera inspection of the well screen or perforations.

Mike Anthony, a Tulare grower, said he plans to have tests done on pumps at his farm where he uses flood irrigation on crops that include cotton, corn and wheat. He also wants to explore using solar energy to power pumps.

Participants concluded the workshop with a visit to pumps that carried water from a canal to irrigate almonds and apricots on the campus farm. Dean Best, a district sales manager with Netafim in Fresno, explained that the pump used a disc cleaning system.

“It uses an automated system, reversing flow and spinning discs to removal material and back flushing automatically,” he said. That sort of system is easier to clean and maintain than a sand filter.

“The media or sand filter can handle a higher load, but if it doesn’t have that need for higher capacity, the disc is easier to maintain,” he said. “It involves taking them out and cleaning them once a year. Soak them in chlorine or an acid solution.”

Water in the pumps can be tested simply for pH levels using a strip. “You can get a meter, but they’re a lot more expensive, and if you don’t use them regularly they tend to dry out,” Best said.

After the workshop, Anthony and Hearn talked of the challenges in Westlands and elsewhere.

“I was out there on the West Side the other day and there are [abandoned] labor camps with weeds this high,” said Hearn, holding his hand a couple feet off the ground. “Westlands is drying up. A lot of it is gone. It’s not as much fun to farm anymore.”

TAGS: Management
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