The following was written as the result of a one-day roundtable hosted by the Center for Irrigation Technology on the Fresno State University (California) campus.  Attendees included farmers, engineers, agronomy consultants, lawyers, educators, and legislative representatives.  The subject was the future of water in California, specifically the San Joaquin Valley.  At the time (January of 1990), California was in the midst of a 7-year drought. 

I was then Water Conservation Coordinator for the Grasslands area irrigation districts, which included Central California Irrigation District, Firebaugh Water District, San Luis Canal Company, Panoche Water District, Pacheco Water District, Broadview Water District, San Luis Water District, Grassland Water District.  My objective was to develop and implement water conservation programs for these Districts. 

The Los Banos area is a fairly complex situation economically, politically, and physically.  Most of the problems are due to the quality and quantity of drainage that is produced.  However, the different types of water rights held by the individual Districts create economic and operational problems.   Much of the area has a high water table and is underlain by artificial drain systems.  Some areas have excess salts and heavy metals.  The Kesterson Reservoirs, where the problem of selenium first drew national attention is located in the Grasslands Water District (private hunting clubs and grazing land, located next to the Kesterson National Wildlife Refuge).

You may also be interested in a more "pro-agriculture" essay on water users and water use.

I welcome your comments...PWCanessa@aol.com    

"Agriculture uses 80% of the water in California."  Anyone involved in California water issues will either say this or hear this at one time or another.   "Agriculture uses 80% of the water in California." There must be something wrong... right?  Well, maybe yes, maybe no.*

That statement usually occurs in an argument over reduction of water diversions to agriculture.  And depending on the context of the argument the statement might be in support of any one of several implications.  Some of the major questions that are continually raised are...

1. Doesn't agriculture pollute the waters of the state, both surface and below ground?

2. Doesn't irrigated agriculture produce salt-laden drainage?

3. Isn't the current allocation of water in the State an unequal use of this essential natural resource?

4. Isn't agriculture inefficient in its use of water?

I would answer...

1. Clearly, in certain instances, irrigated agriculture has contributed to the pollution of waters, both surface and below ground.  The problems with the water supply of the city of Fresno are well documented and the Kesterson Reservoir crisis changed agriculture operations in the Westlands Water District and north forever.   Water pollution, where it exists, must be acknowledged and stopped.  But irrigated agriculture does not result in wholesale, toxic pollution of water in California.

2. Yes, you cannot say "irrigation" without saying "drainage".   It's just a physical fact of life.  Simply put, irrigation water contains salts.  Applied to the soil it adds salts and, depending on the situation, may mobilize salts already present.  Unfortunately crops extract mostly pure water, leaving the salt behind.  To maintain productivity, the salts left in the soil must be removed before yields are reduced or the soil structure damaged.  The way this is done is to purposely leach a certain amount of water through the root zone.  This leaching fraction will carry with it the excess salts.  If there is not sufficient internal drainage, the leaching fraction will in time result in a "perched" water table, reducing the available root zone. In these cases, the leaching water has to be gathered and pumped to the surface for disposal or treatment.

It must be understood that all salts are not toxic.  It is important that questions 1 and 2 be treated separately.  THE MAJOR QUESTION THAT WILL HAVE TO BE ANSWERED SOMEDAY CONCERNS THE FINAL DISPOSITION OF THE SALT THAT MUST BE REMOVED FROM FIELDS IN THE SAN JOAQUIN VALLEY.

3. There is no answer.  A reasonable cop-out would be to say something like this... "the current situation argues for a continual accommodation based on changing economic conditions and population trends along with some abrupt shifts due to physical crisis or political/administrative/court decisions."

But all users, urban, industrial, environmental, and agricultural must acknowledge the validity of each other's claims, and their interrelationship.  If there is no water for agriculture where is the food for a city?  If there is no water for industry, where are the jobs for a city?  If there is no water for the environment, where is the quality of life for the city (and the country)?  And if there is no water for people, where is the city?

4. I don't know.  I've measured irrigations that were terrible- twenty acre-inches/acre of water applied (measured by flow meter) when 8, possibly 9 inches were needed.  The other extreme is severe under-irrigation of fields.  A fair statement is that I can look at any irrigation and probably find something wrong.   But it's a question if it is something environmentally/economically wrong.   And it's a big question if it's something so wrong that it takes priority on the Grower's list, or requires the attention of Government/Private agencies.

However, questions 1 - 3 above argue for one thing, Growers being as efficient as economically possible.  Someone may wonder, why can't agriculture be just as efficient as some other sector? Why does it have to be as efficient as possible.  A few reasons are the amount of chemicals used by agriculture, the amount and type of salts added to or mobilized in the soil due to irrigation, and the diffuse nature of agriculture drainage that prevents convenient disposal methods, such as a city can provide through sewage treatment plants.  Also, agriculture is the user most under pressure.

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The goal for on-farm water management is effective, efficient irrigations...

- effective irrigations produce the desired crop response.

- efficient irrigations make the best use of available water.

An effective, efficient irrigation is the result of a Grower knowing when to irrigate, how much to irrigate, and how to irrigate.

WHEN to irrigate is an agronomic decision, depending on how the crop is to develop.   For example, stressing cotton to prevent excess growth.

Knowing HOW MUCH to irrigate is essential for an efficient irrigation.  The soil moisture depletion should be satisfied. Sufficient leaching must occur to maintain a salt balance.  But excessive deep percolation must be minimized and depending on the situation, surface tailwater controlled.  Growers should have a purpose in mind for each irrigation, soaking in a specific depth of water to wet a specific depth of soil.

Knowing HOW TO irrigate is not just a matter of knowing how to connect sprinkler pipe, or pull head ditches, or start siphons.  It means knowing how to apply water evenly while controlling the total amount of water applied.

Assuming that the Grower knows when, how much, and how to irrigate, then anything that prevents the Grower from irrigating when he wants to, how much he wants to, and how he wants to, is going to reduce the effectiveness or efficiency of an irrigation, or both.   The institutions that participate in controlling the Grower's water supply must not prevent him from using it effectively and efficiently.

But what if the Grower doesn't know when to irrigate, doesn't know how much to irrigate, doesn't know how to irrigate?  Then he has to change.  And change requires knowledge, resources, and motivation.  The Grower has to know what to do, has to have the resources to do it, and has to want to do it.

There is no restriction on knowledge to the Grower.  The UC Cooperative Extension, the Soil Conservation Service and Resource Conservation District Mobile Irrigation Labs, private consultants, and irrigation district specialists are all available to help the Grower.

Resources (primarily money) can be a problem.  However there are many programs of low interest loans (and outright grants) for improvements in irrigation systems.

But finally there is motivation.  The Grower has to want to change, has to want to get better.  What could provide motivation? It might be...

- knowledge, the confidence that he knows what to do, that he won't be making a mistake, that he won't lose money

- increased water prices, an economic decision

- increased power prices, an economic decision

- increased commodity prices, an economic decision

- reduced water supplies, an economic decision

- reduced drainage opportunities, an economic decision

- increased drainage costs, an economic decision

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Irrigation is both an art and a science. Even with the most sophisticated automatic drip irrigation system and computerized irrigation scheduling programs, the Grower's intimate knowledge of his soil and crops will remain an important component in effective, efficient irrigations.

Science has provided a rational approach to the irrigation program.  But adapting this science requires increased management skills and/or capital improvements.  Both are justified only by an economic analysis, the benefits of change have to be greater than the costs.

It may be that in the situations where improvements are available, there just hasn't been a good enough job done by Government agencies, Cooperative Extension, or private consultants in demonstrating the benefits over the costs.  On the other hand, the hard facts of current water, power, labor, equipment, and commodity prices may not justify the effort.  What happens when society is forcing the Grower to improve and the Grower can't economically justify that improvement? See the answer to question 3.

* It's only a point of perspective but that statement should be clarified.  These are very rough numbers but about 1/3 of the rain and snowfall in California (or outside river flows into the state) is diverted for use by man.  Agriculture uses 80% of this diversion. 1/3 of the natural rain and snowfall is used by the environment, the remaining 1/3 remains in the rivers.  Whatever the real numbers are however, the fact remains that the vast majority of water diversions are used by agriculture.

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Additional notes - I pointed out that the toxic question must always be considered separately from the salts question.  There are some other arguments that must be broken down also.  The "double-subsidy" issue is a case in point.   People will argue that it is wrong for the Federal Government to pay Growers not to grow some crops yet give them subsidized water to continue to grow those same crops (especially when they perceive that crop to be surplus).  This may be. It's a point for experts other than myself to argue.  (I would request that they make sure all the questions have been asked, all the questions answered.  These include world marketing factors, quality, and strategic economic policy at the Federal level.)

However, the double-subsidy issue is also frequently brought up in discussions concerning the efficiency of agriculture's water use.  I want to point out that...

1. Subsidizing a crop does not logically mean that irrigation of that crop will be inefficient.  There are several reasons why, both physically and economically, that there generally is no linkage between irrigation efficiency and subsidization of crops.   One of the most basic reasons is that water is a marginal input.  Any added water increases cost of production, except in those Districts which assess a set price per acre per year.  (Pricing water on a set amount per acre per year basis should be re-examined closely.)

This idea of water as a marginal input also works against the idea of water subsidies as source of perceived inefficiencies.  However, it has to be acknowledged by agriculture that whenever the price of water use is low (either because of long-existing water rights, subsidized water, or subsidized power), it is harder to justify the management/hardware changes needed to increase efficiencies (where those improvements can be made).

2. if you take away the crop subsidies it does not logically follow that there will be water available to be taken from agriculture to give to some other sector.  Depending on the location, economics, and the individual Grower, there are alternative crops that could be grown, and there may be an overdraft.

Concerning the development of new water; many will argue for new water developments.   A figure of $200-230/AF as the cost of new water development was put forth and not challenged.  Also not challenged was the argument that very few farms could afford $200-230/AF for water.  The best that could be hoped for is that the cities will pay for the new water, leaving agriculture with its current supplies.  Although the arguments are not without merit, I question that hope (especially considering environmental pressures).  And in any case, making do with current supplies does not bode well for those who would like to farm more ground, nor for those who are currently over-drafting.

Peter Canessa, P.E. - January 18, 1990