Letter to the Editor: Water conservation calculations

Dear Editor:

So, finally, the news mentions what should have been obvious for the last month or so: We're in a drought, again. More likely, we're in a drought, still.

Last year's rainfall, which didn't even reach "normal" here in Southern California, was such a relief that it caused people to lay sod and turn on the taps with the idea that the drought was over, when in reality it never left.

I predict that there will be mandatory restrictions again this year. But instead of reacting to drought after we start running out of water, maybe conserving water should be a proactive goal, because the new normal is projected to be 25% less rainfall for Southern California, thanks to global warming. Built into that projection will be multi-year droughts which will really stress our water supply.

The most effective water conservation programs aren't tiered rates, penalties, or incentives, but ones which provide an individualized household target, customized to the number of people in a household plus the amount of landscaping on a lot. Santa Clara offers such individualized calculations on request, and San Diego offers a home calculator website that can help you estimate how much water you should be using, based on turf grass landscaping. http://www.watersmartsd.org/water-calculator 

So I'm interested in how I'm doing, not compared to my past record (because I've always starved my lawn in the summer, when it gets a tad crunchy) but to what is required for typical turf grass landscaping with a pre-1995 home. Unfortunately, the Santa Clara calculations are unavailable and the San Diego calculator is a little too broad-brush on the landscaping aspect.

So after doing some internet sleuthing, I found a reference to turf grass irrigation requirements for California (Lawn Watering Guide for California - UC Davis http://anrcatalog.ucanr.edu/pdf/8044.pdf) and using conversion factors calculated the following:

Assuming no rainfall, it takes roughly 1.4" of irrigation every week to maintain warm season (e.g. Bermuda grass) turf in the summer, and about 0.4" each week in the winter. That translates to roughly 7 gallons per square foot in the summer, and 1.7 gallons in the winter. For me, that would mean about 58 CCF every billing period in the summer, and about 14.7 CCF in the winter, plus 16 CCF indoor use.

Since we use about 35 CCF each billing period, it seems to me that we've achieved about a 50% reduction in water use through a combination of xeriscaping, water-conserving appliances, and habitual conservation.

This was an eye-opening exercise for me. One of the things that this made clear is that conservation targets shouldn't be based on previous household performance, because that only penalizes those who've already conserved.

I would appreciate it if the City of Downey would make more refined calculations available to the general public, so that those interested can see how they're doing compared to a "benchmark". People might find that they're using far more water than necessary, or far less than they assumed; in any case it would be food for thought.

Joan Niertit
Downey