California is Nuts

Last week, we looked at the fact that California has been in serious drought for the last few years, and touched on the implications this has for groundwater in the region. We also saw that the drought in California has been caused by a simple lack of rainfall. This week, we going to examine the drought a bit more detail, and focus on a key issue - farming.

I mentioned last time that water is important in California, because it has a lot of people and big urban areas like Los Angeles and San Francisco. However, in general, farming is the biggest water user in California. California is the breadbasket of the USA for fruits, vegetables and nuts. For some things, California pretty much single-handedly supplies the whole USA:

Credit: MotherJones

The drought map in this figure is out of date, and things are worse now (see last weeks post for the full picture), but it does aptly make the point that drought is a big issue for the USAs consumption of of some food products. Broccoli and walnuts are the worst offenders (this is some kind of culinary crimewatch) in terms of the water needed per 'unit' - 5.4 gallons are needed for one head of broccoli, and 4.9 gallons for one walnut.

Nuts are the most water draining, as so much water is needed for so little (one head of broccoli is a lot more than one walnut!).  Interestingly, almonds are the worst offender.

Credit: MotherJones

Almonds have become huge business - they are one of the lowest risk investments in the world, as their are so expensive and the price is unlikely to fall. As a result, more and more farmers in California are shifting to almonds and other tree nuts, simply because of their value and investment potential, and increasing demand from China. So, all the almonds produced in California need three times more water than all Los Angeles homes and business'. This really isn't just a theoretical idea - the Central Valley of California (the area that produce almonds) is the driest part of California, and has had the largest changes in well groundwater levels:

Credit: MotherJones

Again, a slightly outdated figure, but the picture it paints still applies. The Central Valley has been massively over-pumped, as nut orchards just keep expanding. Californian law is currently pretty lax on groundwater usages, to the extent that farmers can just drill into the ground and claim the groundwater as there. California is trying to change this, by managing access to all aquifers, but these rules wont come into effect for six years, and there is no way they will be an 'instant fix' - they are still weaker laws than many other Western states, and groundwater works on long, long timescales. Unsurprisingly, farm groups (and likely, the investors that back them) have not been too pleased to say the least, but their vested interests seem to be far less important than California's groundwater problem. 

So - California has got a bit of a problem on it's hands. Next week, we'll look at whether the drought is related to climate change, and if it is ever going to end.