May - June 2010
Vol. 73 No. 3


California water primer

California water balance by year

Delving into California's water situation can be overwhelming. Partly in an effort to develop a clearer picture for herself, Water Committee co-chair Sonia Diermayer has written a set of articles on this and the following page giving background information about water supply and consumption in our state. You can read them in any order.

We have not cited the source of every specific piece of information. Given the herculean task of compiling and analyzing water data for the state, only a few agencies and organizations do this authoritatively. Information presented in these articles is drawn primarily from their publications:

California Department of Water Resources, Water Plan Update 2005 (presents data for the year 2000);

California Department of Water Resources, Water Plan Update 2009 (presents data for the year 2005);

US Department of the Interior, US Geological Survey, "Estimated Use of Water in the United States in 2005", 2009.

California Legislative Analyst's Office, "Improving Management of the State's Groundwater Resources", 2010.

Pacific Institute for Studies in Development, Security and the Environment, "Waste Not, Want Not: The Potential for Urban Water Conservation in California", 2003.

Pacific Institute for Studies in Development, Security and the Environment, "Sustaining California Agriculture in an Uncertain Future", 2009.

Good water management requires better data

One major barrier to reducing California's water use is the spottiness of data. "You can't manage what you don't measure." Measuring and describing California's water is harder than quantifying the cash flow of a large corporation - because water moves into and out of "accounts" by itself. As it melts, percolates into the ground, resurfaces as springs, evaporates into the air, runs off of flooded fields, leaks out of broken pipes, or flows into the sea, we run the risk of counting it more than once or not at all.

Every five years the California Department of Water Resources (DWR) and the U.S. Geological Survey synthesize a vast quantity of data into a big-picture snapshot of total California water supply and use - but the local information-gathering systems on which these reports rely suffer from large gaps. The agencies fill in the missing data through modeling, deduction, and estimates. These processes may use differing assumptions and definitions and yield widely varying results. And by the time they are published, the reports are often quite out of date. (The DWR's compilation for 2005 has just been released.)

One major uncertainty is groundwater supply and use. A recent publication by the Legislative Analyst's Office finds groundwater to provide on average 30% of California's dedicated supply. The DWR on the other hand, shows groundwater as about 18% of supply from 1998 through 2005. California is one of only two western states that do not comprehensively monitor groundwater extraction. SBx7 6, passed in last year's water package (see article, page 10), calls for measuring overall groundwater levels, but still does not require monitoring withdrawals.

Some public utilities do not measure their water distribution. Sacramento and Fresno utility customers have been charged flat rates, so that agencies have not felt the need to meter use. After decades of resistance, they are now required to install meters by 2014. Some agencies, such as the East Bay Municipal Utility District, do not have any mechanism for gauging real-time water use. They essentially monitor customer usage through their bimonthly billing cycle. This makes it difficult to identify when and where peak use occurs and to focus conservation efforts where they could be most useful.

Another obstacle to accurate accounting is the largely invisible leaks reported to be legion throughout urban and agricultural distribution systems. This water is not easily quantifiable. Pacific Institute adopts a rough estimate of 10% for "unaccounted-for-water" in urban use, much of it assumed to be leakage.

Urban water suppliers across the state, as they prepare to comply with the "20x2020" legislation (SBx7 7), also passed as part of last year's state water package, are scrambling to figure out how they will establish measurement baselines for per-capita daily water use, let alone reduce consumption by 20%. The good news is that urban water agencies, at least, are now taking initial steps towards better metering and data-collection.

We need to continue advocating for mandatory groundwater monitoring and metering by irrigation districts. Water-use information must be better disaggregated by timing, user sub-categories, and specific end uses so that agencies can effectively determine where to focus conservation dollars. Individual metering of units in multi-unit buildings is an important step. Smart water meters will also be very useful. The California Energy Commission reports that over half of the state's utilities have installed some smart meters. This technology will help with leak detection and provide real-time water flow data, giving consumers better feedback and hence greater control over their water use. Information is power!

How you can do something for California water

If you want to do something about local and California water issues, get involved through the Sierra Club.

The Chapter Water Committee focuses on a range of state and regional water issues, and in particular on the East Bay Municipal Utility District. To get involved, contact co-chairs Juliet Lamont at (510) 909-5403 or by email to jlamont -at- or Sonia Diermayer at (510) 336-1102 or by email to sodier -at-

For San Francisco water issues, contact San Francisco Group chair Becky Evans at (415) 775-3309 or by email to rebecae -at-

For Marin water issues, contact Group water chairs Michelle Barni at (415) 460-5326 or by email to dmmes -at- or Margot Biehle email sfmargotk -at-

Not sure of your specific interest? Contact Chapter legislative coordinator or call (510) 848-0800, ext. 316