Ever wonder where Irrigation Management data comes from?

CIMIS logo

Introducing CIMIS – which is the California Irrigation Management Information System.

CIMIS plays a big, hidden role in our gardening lives – and in the future you will hear more about it. It is a statewide program in what is called the Office of Water Use Efficiency (OWUE). This “efficiency office” is part of California Department of Water Resources (DWR), which in turn is part of the Natural Resources Agency.

CIMIS manages a network of over 120 automated weather stations all over our state. It was originally organized by the water resources people and UC Davis  to assist California’s big water users (agriculture) to manage their increasingly controlled and limited water resources. 

The idea was to figure out how much rainfall a particular area received. The farmer, knowing how much water a particular species needed over a year-long period, would be able to calculate supplemental irrigation needed to keep the plant at optimal health without wasting water.

When we started to help homeowners reduce turf areas and plant with natives, this data was invaluable in making comparisons between native plant needs and the natural rainfall of an area. Match your plant to your rainfall and happiness ensues. It reminds me of the Dickens character, Mr. Micawber defining his life view, “Annual income twenty pounds, annual expenditure nineteen pounds nineteen and six, result happiness. Annual income twenty pounds, annual expenditure twenty pounds nought and six, result misery.”

So, annual CIMIS data rainfall twelve inches, annual irrigation need for Ceanothus eleven inches, results happiness. Annual CIMIS data rainfall twelve inches, annual irrigation need for Kentucky bluegrass thirty-six inches, result misery.


2 thoughts on “Ever wonder where Irrigation Management data comes from?

  1. One of the problems with CIMIS is that the annual irrigation needs of plants do not take into account seasonal differences in water requirements. Many CA natives (coastal sage scrub, chaparral, etc.) require winter water, while most of the non-natives in CIMIS require year around water. It is helpful to have a very general assessment like this but we really do need to take into account the seasons.

  2. Good point! For example, lawn needs about four times the water we get in the San Diego area annually to stay happy. And it needs that water constantly, evenly, regularly, with no seasonal fluctuations.

    Because almost all of our data and science for horticulture is based on agriculture and turf, our info is skewed by that “norm”.

    Where is our native plant CIMIS equivalent? We need to make this happen.

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