california water reservoirs part 1: a series on california's water supply and climate change

water is a fundamental resource to society

this is a series of blog posts on the california water reservoirs, climate change, and some of the potential risks that climate change can impact to california's water needs. we'll talk about the agriculture sector, the water reservoirs and the state project, the effects of the el nino southern oscillation (ENSO) and the pacific decadal oscillation (PDO), and of course climate change's effects to california's water supply.

The Good Years and the Bad Years

The primary source of California's water comes from the rains and snowpacks that flow into California's watersheds and finally into the reservoirs. Let's take a look at the following graph of the total amount of water in California's water reservoirs from 1970 to 1990.

graph of the total water in california water reservoir from 1970 to 1990

1976 was the fourth driest year on record followed by 1977, the driest year in California recorded. California came very close to austere water measures. 1978 and the years thereafter brought relief with plenty of good rainfall.

Generally speaking during El Nino events, California is wetter during the Spring; during La Nina years, California is drier in the Spring - its larger rainy season; lastly during PDO events, it is also drier.