On today's 41st anniversary of Earth Day, Tucson has something to celebrate about its most precious resource.

The city's total water use declined over the past decade - even as the number of homeowners and other water customers kept rising. And in the overall metro area, water use is growing only slightly, much less than would be expected given population growth.

The declining water use is linked by many experts to the recent economic downturn, to growing concerns about the drought, and to fears of future shortages due to climate change.

But it's also due to relatively small but meaningful changes on a personal level, by residents whose actions are symbolic of the water savings across the region.

A new water-hose timer and shorter showers, for instance, meant thousands of gallons of water savings a month to north-side town-house owner Shirley Feldman.

The plugging of two major outdoor leaks saved thousands more gallons for Carol Roos, a neighbor of Feldman's in Pueblo Villas near North Oracle and River roads.

Their success stories are part of a sharp drop in water use at Pueblo Villas over a year's time, triggered by a conservation campaign.

Tucson has long been a major success story in water conservation nationally. Per-person water use has shrunk significantly since the middle 1970s.

But while the latest water savings have been a cause for celebration among many observers, some have said conservation-minded folks are being punished for their thriftiness. That's because less water sold means water utilities must raise their rates to make up for the lost revenue.

Tucson Water officials acknowledge that has happened but say it's not the major factor in the rate increases that have occurred every year since 2007, with another 8.2 percent increase proposed for fiscal year 2011-12.

It's not clear whether the decline in water use is temporary or permanent, experts say.

The specifics:

• Total water use by Tucson Water customers dropped steadily over the past seven years. It also was lower in 2010 than in 1995, the utility's records show. With population in the Tucson Water service area nearly 100,000 higher since 2000, per-person use has dropped from 164 to 133 gallons daily in that period.

• For the entire Tucson metro area, served by various water utilities, total water use dropped from 2005 through 2008. Although it rose somewhat in 2009, total regional water use is still barely higher than a decade ago.

Nobody really knows exactly what's motivating this much conservation, and designing a scientific study to understand it would be difficult, said Gary Woodard, an associate director of hydrology and water resources at the University of Arizona who has studied water use in this area for decades.

You'd need to look at household water bills, residents' changes in income, their attitudes about their financial future and even the condition of their mortgage, said Woodard.

"I'd say part of the impacts are short-term, but there may be a new ethic of frugality out there," Woodard said this week. "What would be nice to know is how people who are reducing water consumption for financial reasons are doing it. If they're changing their behaviors, then it's probably short-term. If they're changing their mix of water-using fixtures and appliances and landscaping, then it's permanent. "

At 92-home Pueblo Villas, which is served by Tucson Water, the initial motivating factor was to save money. The ways that many residents have chosen to save water includes changed behaviors, landscapes and fixtures. But the leaders of the water conservation drive say that over time the driving force became the environment, and they believe the changes will stick.

Until last year, Pueblo Villas was one of many older multi-family subdivisions and apartment complexes around town with one water meter for the entire development. Individual homeowners' water tabs were folded into a monthly $135 assessment also covering sewer service, trash pickup, insurance and grounds maintenance.

With the association's annual water bill approaching $60,000, the association concluded that individual home metering was needed because nobody knew how much they were using, said Tom Morisky, a leader of the conservation drive.

"The highest user was using 76,000 gallons a month. There was no individual responsibility," Morisky said. "It was shameful. People would leave their hose running overnight."

Meters were installed in May 2010. For the first six months of that year, water use was down for the entire subdivision by 32 percent, said Bernadette Steele, another conservation drive organizer. In that time, low-flow fixtures were installed, leaks were repaired on faucets and toilets, and people took shorter showers. After meters were installed, the association started publishing a monthly newsletter in which each home's water use was recorded.

In the second half of 2010, total subdivision water use dropped another 47 percent, Steele said. People started slashing their outdoor watering, installed gauges and timers on hoses and replaced water-sucking plants with cacti. For all 2010, total use dropped 40 percent from 2009, Steele said.

"You could knock us over with a feather. We never expected that," Steele said.

For Feldman, a Pueblo Villas resident since 1984, conservation was partly a matter of replacing bad habits, she said. For one thing, she had a timer installed on a hose and no longer had to worry about falling asleep and leaving the hose on in her backyard to flood her pansies and marigolds.

Her water use dropped from 12,260 gallons in August 2010 to 1,876 gallons that December. While water use always drops in the winter, Feldman predicted it will rise again only to 3,000 gallons a month by summer.

Roos, another longtime resident, said she was shocked after meters went in to learn that she was using 18,000 gallons a month because she had thought she was being careful. She noticed some dampness in her yard, and quickly discovered two leaks. After they were fixed, her use dropped to 3,000 gallons per month.

A retired environmentalist and water consultant, Priscilla Robinson, thinks most of these savings reached across the community will probably last because she has watched water consumption fall over the last 25 years as the price to buy water has gradually risen.

Morisky agrees. Even when the economy comes back, he expects most of these water savings to last. "Money is always going to be an issue. Plus, people are getting more aware."

How are Southern Arizonans doing on making the most of their resources? See for yourself

Statistics from air quality to water harvesting show how conservation efforts are faring in the Tucson area this Earth Day:

Recycling

Recycling rates have stuck at 21 percent to 22 percent of all trash materials since Tucson's curbside program with the blue barrels began in 2003. One reason: The variety of recyclables the city accepts has also stayed at or near that level. City officials hope recycling rates will improve starting July 2012, when a new center that can take more kinds of recyclables is due to open, said Cristina Polsgrove, a Tucson Environmental Services Division spokeswoman.

Bus ridership

After rising seven straight years, Sun Tran ridership dropped 5.4 percent in fiscal 2009-10 and has dropped 4.8 percent for FY 2010-11 through March. Reasons: a fare increase in August 2009, the recession and a seven-day bus strike in August 2010, said Michelle Joseph, Sun Tran's marketing director.

Air quality

No violations of federal air quality standards have occurred since 1999. Carbon monoxide levels have declined steadily since the 1970s. Continuing a decade-long pattern, in 2010 at least 94 percent of all days were rated good for ozone, fine particles and coarse particles.

Petroleum usage

By encouraging the use of alternative fuels such as electricity, natural gas, ethanol and biodiesel fuel in vehicles, the area's regional Clean Cities Program saved nearly 50 million gallons of gasoline from 2005 to 2009, says the Pima Association of Governments.

Vehicle miles traveled

Rose from about 17 million miles total daily in eastern Pima County in 1998 to 26 million in 2008 to 28.94 million daily today, the Pima Association of Governments says. That's about 80 percent of Earth's closest approach to Mars.

But because new census figures show Pima County's population is lower than previously thought, the recent estimates for mileage driven may be too high because they were based on older population estimates.

Electricity use

Total electricity sales for Tucson Electric Power fell 0.8 percent in 2010 from 2009. The troubled economy and a utility push for energy efficiency among its customers could have contributed to the decline, said TEP spokesman Joe Salkowski.

Water harvesting

In 2008, 60 to 70 cistern-based or other water-harvesting systems were installed monthly, says the Pima Association of Governments. Since then, the number of systems installed has probably stayed the same. But the number of water-saving workshops run by the nonprofit Watershed Management Group - where people learn how to install harvesting systems - has risen from 15 in 2007 to 68 in 2010. About 2,000 people have attended, says director Lisa Shipek.

Contact reporter Tony Davis at tdavis@azstarnet.com or 806-7746.