Farm water costs mimic desalting price tag

Farm water costs mimic desalting price tag

The price some farmers are paying for water to keep crops alive makes the cost of desalting sea water downright reasonable, but California’s seaside residents are not convinced.

Even though the experience for desalinating water from the Pacific Ocean as it borders many California communities has been mixed, many inland farmers who may never benefit from the process think it should become the top alternative to current sources of water supply.

Their arguments begin with the supply of water available – the Pacific Ocean. Cities, counties, and communities bordering or near the ocean from the Oregon border to Mexico are the obvious candidates.

A few have built or at least planned desalination plants. Some of those are operating, one or two have been shut down, and at least one is on the verge of reopening.

Traditionally, the argument against desalination has been the cost of building and operating such a facility. Materials for the construction and operation of ‘desal’ plants are expensive, partly since they are sophisticated and scarce. They are not found on the back shelf at Lowe’s or Home Depot.

The California desal issue was well covered in a recent New York Times article circulated by the California Department of Food and Agriculture (CDFA).

Surprisingly it made no mention of the desal plant in western Fresno County which is removing salt from irrigation tail water and mixing it with fresh irrigation water before returning it to the fields, and doing it with solar energy.

Admittedly, the Fresno County plant is tiny by comparison with the large facility under construction near San Diego, or any of those built or being planned by other seaside communities.

Existing desal plants in California all employ the principle of reverse osmosis, though among the plants operating elsewhere in the world, including the Middle East and China for example, plants employing other methods of prying salt from ocean water are operating.

Besides the expense of the sophisticated construction materials used in reverse osmosis plants, large amounts of power are required as well in their operation. It takes a lot of energy to push water through the minute spaces in the special membranes that prevent the salt from passing through.

Another issue mentioned in the New York Times article is the disposal of the salt that accumulates with daily operation of a desal plant.  Some objections have been voiced to returning the volumes of salt to the ocean.

It didn’t discuss the possibility of cashing in on the salt for human use. After all, a large part of the southern end of San Francisco Bay is a salt factory, employing naturally occurring brackish water dehydrated by sunlight.

What happens to expensive desal plants once rains bring an end to the drought as we know it?  A few years ago, Australia turned to desalination amidst a historic drought, building six plants.  Four of them have been idled since rains have returned.

The article circulated by CDFA made no mention of the possible use of water from the Pacific Ocean to bolster supplies of irrigation water employed by farmers. Extracting and transporting water would incur high costs.

But who’s to say that irrigation districts in the Central Valley could not strike a deal with a coastal community to accomplish the task.

The results the San Diegans have with the nearby plant under construction will provide background for possible future expansion of desalination as a viable means of producing potable water for millions of Californians.

Some of them might be farmers in your neighborhood or in the next county.

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