The city of San Diego on Friday unveiled its plan for cutting citywide water consumption by 20 percent.

It plans to ask residents in single family homes to cut 45 percent of their outdoor use and 5 percent indoors. The city is effectively establishing a ceiling for your use. Exceed that maximum, and you’ll pay penalty rates and face possible fines.

So what does that actually mean?

Let’s examine the water use of three public officials: City Councilwoman Donna Frye, Mayor Jerry Sanders and Scott Peters, the port commissioner and former city councilman.

(Why them? We have their water bills for the last five years, because public officials’ bills are public records. We don’t know Peters’ current usage, but we have his historical bills during his time on council. The cuts will be based on past usage.)

  • Donna Frye

    Previously annual average (from July 2004-June 2007): 98,182 gallons a year.

    New ceiling in July: 84,518 gallons a year.

    Must cut: 13.9 percent.

    Frye, like many public officials, conserved at home in 2008. She used less than her ceiling, so she won’t have to cut more. She’ll just have to keep up the conservation she’s already done.

  • Jerry Sanders

    Previously annual average: 226,646 gallons.

    New ceiling: 152,833 gallons.

    Must cut: 32.5 percent. (The mayor used more water outside than Frye, so he has a larger percentage cut.)

    Sanders also won’t have to conserve more. His household’s 2008 consumption was already 44 percent lower than in 2006. He’s below his ceiling.

  • Scott Peters

    Previously averaged: 843,085 gallons.

    New ceiling: 535,500 gallons.

    Must cut: 36.4 percent. (Peters used more water outside than Sanders or Frye, so his percentage cut is the highest of the three.)

    We don’t have Peters’ bills for all of 2008, so we don’t know whether he’ll have to cut further or not. He started reducing use in 2008, but was still on target to use above the ceiling when we last received his bills.

    Peters consumed so much that he will fall into the city’s heavy-user category. By the city’s methodology, Peters used 18,700 gallons indoors in his lowest months. He’ll only get credit for 14,960 gallons of that as being interior use. The city says 14,960 gallons is enough water for a family of 10, suggesting that Peters (who has a family of four) was watering outside during the winter. Just 12 percent of San Diegans use enough to fit in that category.

    That’s one flaw in the city’s plan. Its estimate of interior use (which won’t be cut as much) can be inflated if a resident unnecessarily watered plants or a lawn during the winter.

So how did we calculate all this? Let’s look at Frye’s consumption for an example of how it works. Math alert. Stay with me.

Frye consumed an average 98,182 gallons at home annually between July 2004 and June 2007. By my calculation, if the city’s plan is approved, she’ll be allowed 84,518 gallons annually starting in July. The city will ask her to use 13.9 percent less — to save about 14,000 gallons.

The city plans to cut a house’s interior use by 5 percent, its exterior irrigation by 45 percent. It will identify a house’s interior usage by finding the lowest 60-day period of use during the winter months from 2004 to 2007, when most people are irrigating less outside because it’s cold(er) and wet.

Frye’s lowest two months were November and December 2004, when she used 6,358 gallons per month. That gets trimmed 5 percent. So Frye has a guaranteed 6,040 gallons. She gets cut by 318 gallons inside each month, enough water to run a shower for two hours.

The city will use that low period as the basis for figuring out how much water Frye sprayed outdoors the rest of the year. It’s not completely accurate — a household’s baseline could be inflated if its residents watered outdoors during the winter.

According to the city’s methodology, Frye didn’t use much for irrigation. During the time in question, she averaged 21,886 gallons each year outside, following the city’s methodology. That gets cut 45 percent, meaning she could use 12,037 gallons outdoors each year without being penalized.

The City Council’s natural resources subcommittee is scheduled to discuss the allocation methodology Wednesday at 2 p.m. on City Hall’s 12th floor.


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