California's Governor Arnold Schwarzenegger declared a state of emergency because of severe drought after three dry winters left reservoirs at their lowest levels since 1992.
Farmers have been particularly badly hit in a state which is the largest producer of food and agricultural products in the US.
Sarah Wynn, who owns an avocado grove in Temecula, describes the impact of the drought forcing producers to abandon their farms.
We have about four acres of avocado trees, which may sound small for a farm, but the average grove size is not far off that.
Most of the groves in California are small family-owned plots although they produce 90% of the avocados grown in the US.
Sarah Wynn: The lack of plentiful water leaves groves with salt burn
We need a lot of water to be able to produce avocados and the drought is forcing us to rethink our plans for the future.
Last year we had a mandatory 30% reduction in our water supply.
As a result, the trees are looking quite sorry for themselves, despite the fact that our water usage was higher than allowed for the last month and we had to pay a stinging penalty to the water company.
This year we still have the 30% mandatory reduction with the prospect of a further reduction to be announced in spring.
So the rising cost of water will probably prevent us from continuing to grow avocados.
The avocado trees need a good soaking to wash accumulated salts out of the soil, and we're not getting the rain or water to do it.
We have considered replanting with a less water-intensive crop, but it's not worth it as an investment
We haven't actually had any trees dying because of lack of water. The problem is that without plenty of water, the trees won't bear fruit.
There is a base level of water required to keep avocado trees alive, but they don't produce fruit at this level. Water given over and above this amount results in fruit. If we don't give the trees that extra amount of water, the grove becomes effectively a rather expensive landscape.
Years ago when the avocado groves were first planted in California, water was available and there were tax incentives to grow food. The tax incentives no longer exist and water is becoming scarce.
We don't often make much of a profit with the avocado grove. We've had the farm for six years and we've made a reasonable profit only for two years.
We cannot rely on the grove income alone.
We have considered replanting with a less water-intensive crop, but it's not worth it as an investment.
We could remove all of our 400 avocado trees and replant with olive trees for example.
But then the cost of watering them for five to seven years until they mature enough to bear fruit is huge and it is a risky step considering how insecure our water supply is.
Our next door neighbour has an orange grove. Oranges need just as much water as avocados, but are less commercially viable.
Sarah Wynn: This is one of the abandoned groves in our area
So she had to give up watering her trees a few years ago and fruit produced just rots on the ground.
We have quite a few avocado groves in this area that have been abandoned too. The avocado groves in this area will eventually disappear because of the commercial pressure of water.
One negative side effect is that the abandoned groves are a wildfire hazard, which we could really do without. Even as I say this a new fire has started in Camp Pendleton - there's a great big plume of smoke across the valley right now.
Avocados are just one crop of many grown in California, but many seem to be in the same situation.
The question in my mind is, can the rest of the US grow enough food to support itself if California has to severely reduce production due to water shortages?
California is a great place to grow food because of all the sun we get, but unless we can save more of the fresh water falling from the sky and get it piped here, farmers will gradually stop producing food.