Watering your lawn in the Twin Cities suburbs these days takes a bit of timing. This week, Richfield joined a growing list of communities placing permanent limits on lawn watering.

From May through Sept. 10, watering in Richfield will be banned from 11 a.m. to 4 p.m. Though the city's restrictions are less severe than many, city officials said the new ordinance is an important step in dealing with long-term water conservation in a growing metro region.

"I think a lot of this is kind of changing our culture around water," said City Council Member Michael Howard.

Richfield also is requiring all new or extended automatic irrigation systems to include a moisture sensor to prevent them from operating while it's raining.

Council members rejected a proposal to adopt the even-and-odd-day watering system used by many suburbs but suggested it might be worth considering in the future.

The seven-county region uses about 113 billion gallons of water each year, according to the state Department of Natural Resources.

But usage jumps sharply during the summer: about 568 million gallons a day, compared with about 265 million gallons daily during the cooler months.

Public works officials are hoping to hammer down that spike a bit through watering restrictions. The high summertime usage means that water systems must be designed and built to handle that volume, even though they're running well under it for much of the year.

"Building extra wells, extra water mains, extra treatment facilities — that's a lot to spend for water you're going to throw on your lawn," said Joe Richter, a DNR water appropriations hydrologist.

Adopting an even-odd watering schedule, as many suburbs have done, can cut peak usage in half, Richter said. He added that even tighter controls would be a good idea.

"I would encourage cities to go from an even-odd schedule to twice a week," he said. "Most lawns don't need to be watered every other day."

Richter estimated that about two-thirds of the Twin Cities suburbs have adopted some form of watering restriction. However, neither Minneapolis nor St. Paul has any nonemergency watering limits, although both cities encourage conservation.

But since the two large cities get their water from the Mississippi River rather than underground, they don't have the concerns about depleting the aquifers that the suburbs face. Bloomington buys much of its water from Minneapolis and also has no ongoing usage restrictions.

Richfield city leaders said they'd go easy on enforcement as residents get used to the new restrictions. This year's ban won't start until mid-June, 30 days after the City Council's action.

Officials who see a violation in the early going will take the opportunity "to educate people, not cite people," Richfield Mayor Debbie Goettel said. "And that's how the city does it: friendly."

John Reinan • 612-673-7402