The warmer weather has apparently caused some locals to forget to turn off the tap and conserve water whenever they can.

In May and June, the city as a whole failed to attain a 15 percent reduction in water use mandated by purveyors. And officials say Simi residents could come up short again this month.

Simi gets its water from two sources: the Ventura County Waterworks District No. 8, which is overseen by the City Council and provides water to about 60 percent of Simi, and Golden State Water Company, which serves about 13,300 households.

Both purveyors purchase their water from the Calleguas Municipal Water District, which gets its water from the Metropolitan Water District (MWD).

After three years of drought, both MWD and Calleguas last July called for a mandatory 15 percent water use reduction for fiscal year 2009-10 and beyond.

Although Golden State customers were doing a good job meeting the monthly goals earlier this year, they started to slip backward once summer hit, missing the 15 percent mark by 7 percent in May and 5 percent in June.

“And it looks like we’re (missing the mark) in July,” said Golden State District Manager Ken Petersen, who oversees a region that includes Simi Valley.

Despite exceeding its allocation in May and June, Golden State customers in Simi did meet the 15 percent reduction for the fiscal year, which ended July 1. They actually did even better, reducing their water use by 20 percent, Petersen said.

Still, he said, while customers did a “fine job” last fiscal year, the time to conserve is not over.

“Now we’re starting a new year with these two higher (months), and we’re afraid that we’ll be behind as we finish out the summer,” he said, adding, “We’re not out of the woods as far as water is concerned.”

Petersen partly blamed the overuse on the company lifting premium charges in March for customers who exceeded their allocation.

Golden State is currently encouraging its customers to voluntarily maintain their water usage at or below the allocation levels they have on their bills, but the company warns that if customers do not, premium charges could be instituted again.

Because that hurts the pocketbook, it does get a response, Petersen said.

Unlike Golden State, the city’s waterworks district struggled much of the year to meet its monthly usage goals.

The city met or came close to reaching the 15 percent reduction most months, but it was far off the mark in November, March and May.

In June, the usage goal was 673 million gallons, but waterworks customers used slightly more at 679 million gallons.

Looking at the whole year, Public Works Director Ron Fuchiwaki said waterworks customers did “pretty good.”

“Overall we didn’t reduce as much as we had hoped. We were looking for 15 percent, but we didn’t quite get there.”

Fuchiwaki said the city is still waiting to hear from Calleguas what its final water usage was for the year.

Both the waterworks district and Golden State could suffer severe financial penalties from MWD if users did not meet the 15 percent mandate—and those fines would be passed on to customers.

Golden State appears to be in the clear. Fuchiwaki is hopeful that the waterworks district won’t incur any fines either if the Calleguas service area as a whole meets the target.

One reason the city may not have been as successful as Golden State in reducing its usage is because the waterworks district relied on the honor system, simply asking residents to better manage their water use.

“We focused our water conservation program on education and outreach,” said Wanda Moyer, environmental compliance program analyst. “Once you tell people they can save some money (by conserving), they’re a lot more open to listening to what you can share with them instead of hammering them with a fine.”

Moyer said awareness about the need for conservation has increased over the past year but residents must continue to watch their water use.

“It’s good that we’ve made this progress, but we still have to remain diligent because . . . we still have our hottest weather ahead of us,” she said.

For more information about the city’s water conservation program, visit www.simivalley.org/ waterconservationprogram.

Golden State customers can learn more at www.gswater.com.