9 January 1998

Water worries mar

a farming paradise

California is one of the most productive agricultural areas of

the world, with the soils and climate to grow almost anything.

But cheap irrigation water supplies may not be as plentiful in

the future as they are now. Leonard Goymerac reports

SALINITY poses an increasing problem for Californias prosperous agricultural sector. The main problem is that water from the Colorado River – the main source of irrigation – is inherently saline.

Each acre-foot of irrigation water (the amount of water it takes to cover one acre with one foot of water) contains 1t of salt. To combat the problem, fields have subsurface collector drains which remove saline water and then empty towards the Salton Sea. The hot climate causes increased evaporation, thus compounding the problem.

In Californias Imperial Valley, one of the most productive agricultural regions in the world, with almost a billion dollars in crops grown annually, this is a serious problem.

According to the agricultural commissioners 1997 annual report, total agricultural production in 1996 amounted to £560m. As a measure of how agricultural production affects the state, for every £1000 of total gross value produced, £210 of personal income is generated in related jobs.

Water diverted from the Colorado River to the Imperial Valley is governed by the federal governments Bureau of Reclamation. Each year the Imperial Irrigation District is asked by the US Bureau of Reclamation to estimate the amount of water it will need. The Imperial Irrigation District (IID) receives approximately 2.77 million acre-feet per year.

Taken for granted

Water is not taken for granted, though. Over time, ageing canals have had seepage losses, which initiated an innovative mutual agreement by two concerned agencies.

The MWD, or Metropolitan Water District, delivers most of its water supply to Los Angeles, and the Imperial Valley Irrigation District to agricultural supply. A deal was struck whereby MWD would fund the lining of the canals, thus saving 70,000 acre feet of water. In return for funding, MWD would have its share of water increased by the amount saved.

FACTSANDFIGURES

The 1996 Imperial Valley crop survey covered 210,000ha (520,000 acres). Of this, 37,000ha (92,000 acres) is planted with up to 70 varieties of salad vegetable. The biggest in area terms are:

000 ha000 acres

Carrots6.716.5

Lettuce8.922.1Cantaloupes

(Spring)6.115.1

Onions4.812.0

Acreages often shifts according to expected demands. For example, in 1991 67ha (167 acres) were devoted to growing aubergine. In 1993 the acreage fell to 2ha (5 acres).

Livestock production accounts for 318,952 head of feedlot cattle, and 250,000 sheep. Field crops range from alfalfa to cotton and sugar beets.

Vegetable crops range from asparagus to watermelons, with over 44,000ha (109,000 acres) devoted to production. Fruit and nut crops ranging from dates, to pecans, grapes, peaches, mangos and guavas appear in the lush valley along with important seed and nursery products.

CROPVALUES 1996

According to the Imperial Valleys agricultural commissioners report, total 1996 agricultural production value was £600m, a 19% increase over the previous year.

Some representative field crops, in gross values (£m):

1. Alfalfa £1.12(cubed and chopped)

2. Cotton (baled)£6.44

3. Sugar beet£28.57

4. Wheat£11.19

5. Sudan Grass£34.0

Some representative garden crops, in gross values:

1. Asparagus£16.50

2. Carrots£39.27

3. Lettuce£29.35

4. Cantaloupes (spring)£29.08

5. Onions£12.25

Some representative permanent crops, in gross values:

1. Dates£7.80

2. Citrus (all combined)£1.07

3. Honey£1.18

Above: Two faces of Californian agriculture – 300,000 sheep come into the state from neighbouring areas each winter. Despite having to compete with more exotic crops, wheat is still an important part of the Californian agricultural economy.