City of Irvine, California

After a drought hit California in 1986, the city of Irvine’s water purveyor imposed landscape irrigation requirements based on a then-radical concept: evapotranspiration (ET) rates. To meet these new requirements, the city had to reduce water use. As a result, some of the 700 acres of publicly owned landscape began showing signs of stress, including the many miles of expansive streetscapes for which the city was known.

It appeared impossible to meet the water district’s new requirements—until the city switched to the U-Series Nozzle, the first plastic nozzle on the market with a patented two-orifice design for superior water distribution. Today, tens of thousands of U-Series nozzles keep Irvine’s landscapes looking green on less water.

City’s Medians Pose Efficiency Problem

Located in Orange County, 45 miles south of Los Angeles, Irvine is the largest master planned community in North America. Its 43 square miles have been carefully conceived to balance dense residential areas with large amounts of open space and maintained landscape. Approximately 700 miles of roadways are lined with wide parkways and divided with turfed medians for aesthetic appeal.

The turfgrass in Irvine’s medians has always required an extraordinary amount of water. The excess water has been needed to compensate for the surrounding hot asphalt that drives up ET and high velocity winds that reduce application efficiency.

“We irrigated for the worst conditions on our medians, which basically meant we were almost flooding areas where we couldn’t get proper distribution,” said Louie Martinez, Irvine’s landscape supervisor. Complicating matters was Irvine’s heavy and compacted clay soils which reduced infiltration rates and led to run-off into the surrounding streets.

Then a drought hit that would last seven years, and water became scarce. In response, the Irvine Ranch Water District (IRWD) established a water budget and a tiered pricing system based on ET rates gathered by IRWD-owned weather stations. The tiered pricing system rewards conservative users and penalizes excesses. The city must stay within 100 percent of the water district’s allocation or pay double and as much as eight times the base price for excessive use. “Along with the need to keep water off the streets and to have healthy looking turf, the city had an economic motivation to become more efficient with water,” said Tom Ash, horticulturist and conservation specialist for IRWD.

Water Management Programs and the U-Series Nozzle

To meet the IRWD budget, the city began water management programs and made major investments in its irrigation system, which included Rain Bird 1804-SAM-PRS pop-ups. While the programs and equipment did result in much greater efficiency, new problems arose. “When we started pushing the envelope on water applications, the weak spots of the irrigation systems became evident,” said Martinez. “The first noticeable weak areas were in our streetscapes where we started seeing dry spots around the heads.”

To investigate the problem, the city monitored several sites and conducted catch-can tests to measure uniformity of distribution. Because of the medians’ adverse conditions, it was difficult to achieve a high degree of uniformity. Many of the heads were losing as much as 30 percent of their water to the wind.

In 1994, Rain Bird was poised to unveil a new nozzle with two-orifices, one to water close-in and the other for further out. Familiar with Irvine’s challenges, Rain Bird offered Irvine the opportunity to test the U-Series Nozzle. “We installed them on some of our medians and, without changing the timing or anything else, we had an immediate response: the dry spots around the spray heads disappeared,” said Martinez. The U-Series Nozzle’s second orifice is designed for close-in watering to minimize dry spots around spray heads. Its patented design produces a spray from both orifices that combine to form a continuous water stream to more uniformly cover an entire watering area (the U stands for uniform). U-series has a lower spray trajectory and bigger water droplets than most nozzles, making it less susceptible to wind drift. “We found that the U-Series Nozzle’s droplets were more consistent to the outer edge of the radius, there was an even distribution of water and the undercut nozzle sprayed water adjacent to the sprinkler where we were having dry spots,” said Martinez. “The U-Series Nozzle’s low scheduling coefficient also allowed the irrigation schedule to remain unchanged. Because U-Series nozzles are more efficient and distribute water more uniformly, they do more with less water and in less time. “Our initial order was 40,000 for our medians throughout the city, and now the U-Series is the standard nozzle on all turf applications,” said Martinez. “We’ve literally changed tens of thousands of nozzles to the U-Series and it’s been well worth it.”

The city has also upgraded from four-inch pop-ups to 1806-SAM-PRS six-inch pop-ups on medians and throughout the city. The six-inch pop-ups clear taller turfgrass, the patented in-stem pressure regulator (PRS) maintains constant outlet pressure and the built-in Seal-A-Matic™ (SAM) reduces low-head drainage.

The results have been significant. Even though Irvine has added new land for its growing community, it has reduced water use with the U-Series Nozzle.

“This is one utility bill that has stayed level for about three years, even during 1996 and 1997, two of our hottest years on record,” said Ash.