RENO — A new three-day watering week schedule recently approved by the Truckee Meadows Water Authority Board of Directors shouldn’t be cause for concern for the water supply, even in the current drought, according to John Erwin, the agency’s director of natural resources, planning and management.

“The watering supply is more than adequate to get through the (watering) season,” Erwin said Wednesday.

The schedule approved at last month’s board meeting was a provision of the Truckee River Operating Agreement, a negotiated settlement between the federal government, the Pyramid Lake Paiute Tribe, the states of Nevada and California and TMWA. Erwin said until 90 percent of water users in the area were retrofitted with meters, the local government would enforce twice-a-week watering, an ordinance introduced in 1986.

Erwin said that the 90 percent mark for metering was finally reached in 2007, giving TMWA the authority to provide an alternate watering schedule.

“We opted for the three-day schedule,” he said. “We could have gone to water-any-day-you-want. Well, that doesn’t help too much when it comes to managing your facilities.”

TMWA’s treatment plants cumulatively can handle up to 108 million gallons per day (MGD). Combining that total with groundwater pumping comes out to 170 MGD.

“That’s a significant investment,” Erwin said. “If everyone watered on the same day, we could potentially spike up to that.”

But water engineers and treatment employees prefer to maintain some level of reserve capacity, Erwin said.

“The last thing you want to do is run everything at 100 percent and have everything break,” he added.

But with most people on the meter now, individuals have control over their water usage, which translates to control in their budgets, Erwin said. Other factors have come into play that have signaled that demand has not increased, but remained fairly consistent during the last four years or so.

“Economic conditions have come into play,” he said. “We’ve been in fairly dry conditions climatically, so you hear a lot about drought. The whole western United States is sensitive to weather and weather-related water supply. We’ve seen a change in our population’s understanding of water use and we’ve seen characteristic changes in landscaping. A lot of people are tired of mowing their lawns.”

TMWA officials conducted an experiment in 2007 and 2008 in which they tested different watering schedules in three different neighborhoods. One set of residents was told they could water whenever they wanted, another was told to water three days a week and the control group was on twice-a-week watering. The results were clear.

“Lo and behold, we found a lot of folks were watering three days a week (anyway),” Erwin said. “We were redeeming their behavior and providing them the opportunity to play by the rules.”

Scott Tyler, a hydrologist with the University of Nevada, Reno, has reservations about the extra watering day. He said he prefers the former schedule because he thinks it could reverse the attitudes of some residents who might be tempted to use more rather than less water.

“I’m personally a fan of watering twice a week as both a hydrologist and as a pretty efficient way to keep grass growing,” Tyler said. “My sense is people are pretty used to two days a week and this would make a change in people’s mindset of how they irrigate and water. … That we live in a dry climate, to go back to more frequent watering is a bit of a step in the wrong direction.”

Though he admitted this particular area is not his specialty, he worries that the arrival of runoff from recent snowstorms earlier in the spring season rather than later can affect the summer supply.

“Now that it’s coming earlier in the year, we can’t hold it back as runoff,” he said. “It all goes to Pyramid/Lahontan because we don’t have the storage capacity (in other reservoirs). It’s a common problem.”

But Erwin said keeping to a three-day schedule offers an advantage in that on Mondays, the one day on which no one is allowed to water under the new schedule, TMWA’s operations employees can take the day to “recover” from the weekends. Most residents use the weekends as their big watering days, so if no one waters on Mondays, workers can schedule maintenance of systems and refill storage tanks as needed.

According to Shawn Stoddard, senior resource economist for TMWA, the water authority will begin to collect data over three years to determine whether residents’ watering habits change as a result of the alternate schedule.

“Given this is a transition year, it would be useful to collect the data and see how people are transitioning and confirm what we know, (which) is people are not going to use more water; they’re just going to change how they spread it out,” Stoddard said. “That’s like me saying just because the gas station is open on Sunday you’re going to go out and buy more gas for your car. It just doesn’t work.”