IN THE GARDEN MORE ON WATER-SAVING WAYS.

Byline: JOSHUA SISKIN

A recent column addressing the increased use of evapo-transpiration sprinkler system controllers - self-programming and self-adjusting automatic time clocks - presented an incomplete picture of the subject.

I had been informed by industry sources that by 2010, all new controllers (time clocks) would have to be ET, or as some call them, smart controllers. In response, the Metropolitan Water District informed me that a statewide task force had indeed recommended mandating such controllers by 2010, but that no legislation had yet been passed.

I was also unaware that the city of Los Angeles had installed and provided rebates for more than 500 smart controllers and is giving away another 100 later this month. Still, there is blanket policy for granting these rebates in the city. Interested DWP customers can call [phone] for more information.

According to Carlos Michelon, an associate engineer at the MWD, cities and communities in San Diego, Orange, Riverside and parts of Los Angeles County are also currently offering rebates for smart controllers. Pasadena, Glendale and Burbank are developing programs as well.

MWD officials are aware of 20 manufacturers of smart controller products that reportedly meet the criteria established by the Irrigation Association, a national organization focused on water conservation based in Falls Church, Va. Field trials are under way to determine which controllers are best. Michelon emphasizes that a comprehensive study of bottom-line water savings from this technology will be completed by spring 2007.

Speaking of manufacturers, I received an e-mail from Andrew Davis, who produces smart controllers in Winnetka, right in our own back yard. His controllers, which are available for rebate by the Metropolitan Water District and are less expensive than some competing models, program and adjust sprinkler watering time based on precise measurement of solar radiation, as well as precipitation. You can learn more about Davis' clocks by calling him at [phone], or online at www.weatherset.com.

The MWD is also looking at promoting greater use of new low-flow rotating stream spray nozzles and micro-spray irrigation, both of which can yield up to 50 percent savings of landscape water.

Conventional spray sprinklers can easily be replaced with rotating stream spray nozzles. These rotaries apply water much more slowly than spray sprinklers and, consequently, runoff is significantly reduced.

While rotating stream spray nozzles are best suited to lawn, ground-cover areas and slopes, low-volume microspray irrigation, an embellishment of drip irrigation, is meant for perennial, shrub and flower-bed applications.

Microspray sprinklers, jets or emitters work best in drip tubing. It's fairly easy to connect drip tubing to a sprinkler valve. All you need is the appropriate adapter, pressure regulator and filter, plastic pieces that can be found in most home-improvement centers.

There are distinct advantages to microspray - as opposed to drip - irrigation. Most important, perhaps, is that you can see at a glance whether water is flowing through a microspray jet, while drip lines or emitters may clog without notice. Also, a single microspray sprinkler can cover a larger area than a single drip emitter.