With thirsty lawns and trees in need of water, suburban residents are struggling to get their home landscapes through a dry summer while obediently adhering to water conservation restrictions.

City after city now has adopted watering restrictions and stepped-up rates for high water usage, and some residents are shy about watering even when it's allowed, fearing they are wasting a precious resource.

Yet there is no water crisis in Minnesota. The Twin Cities area has more water in lakes, rivers and groundwater reserves than almost any other metro area in the country.

So, when is it OK for an environmentally conscientious citizen to water?

The answer depends in part on where you live.

Minneapolis and St. Paul, which get virtually all of their water from the Mississippi River, haven't restricted water use since the drought of 1988. For now, pumping water from the Mississippi onto your lawn won't stress any resources.

But some suburban cities that rely on wells have seen water levels drop precipitously during summer months, even though they may restrict lawn-watering on an odd-even day basis. Experts say there is reason to be concerned about the long-term health of aquifers from which some cities draw much of their water, via wells that range from a few hundred to 1,000 feet deep.

In Dakota County, water levels in environmentally sensitive fens have dropped when nearby wells sucked up too much water. In Chanhassen two years ago, two city wells ran dry. Some cities have had to revamp wells to pump deeper to get sufficient water.

And while water levels in aquifers hundreds of feet below the surface fluctuate according to season, making trends hard to discern, a Metropolitan Council expert says the water level in an aquifer used as a water source in Scott County appears to have dropped about 100 feet since 1980.

Concern about water consumption in a still-growing region is sharp enough that state and metro officials are steering people toward more careful water use.

"Just because it's there, wasting anything isn't a good idea,'' said the state Department of Natural Resource's water appropriation manager, Laurel Reeves. "It's especially important this time of year for preserving the resource that we have in case this is a prolonged drought.''

State law reflects a general conservation ethic, Reeves said.

"It's not that there is a problem imminent or occurring, but that we want to be looking forward so we don't have an issue,'' Reeves said. "We are charged to not only allow for use currently but to be certain that there is a supply available for future generations.

What cities have experienced

In Eden Prairie, where officers patrol at night to ticket homeowners who violate sprinkling restrictions, Public Works Director Gene Dietz said he has been called a "water Nazi'' for enforcing city water conservation rules.

Eden Prairie is not short on water and plans to open another well this summer. But when the city pumps for lawn watering during the summer months, Jordan aquifer groundwater reserves drop by 100 feet, Dietz said.

Wells must be modified

Typically, the aquifer recharges and gains back the 100 feet of water in the winter, but the lower summer level has forced the city to modify two wells to pump deeper.

While no one knows how much pumping would be too much for an aquifer, Dietz said, it takes years for surface water to seep back through rock to the aquifer. "You just know that if you over-pump you are going to ruin it,'' he said.

Chanhassen in fact did over-pump. In 2007, two of the city's wells in the shallow Glacial Drift aquifer simply went dry. "We had to shut the wells off -- we were pumping it down into air,'' said Chanhassen utilities superintendent Kevin Crooks.

"We don't know what happened. It wasn't recharging the way it had in the past. We had to dig two more wells at great expense.'' Now Chanhassen carefully watches the wells it has in the Jordan aquifer.

In January, state law will require all metro cities to have "conservation rates" that charge heavy users more per thousand gallons for water. The law extends to all Minnesota cities in 2013.

In Woodbury, where 35 percent of homes have automatic lawn irrigation systems, the state directive has reinforced city attempts to encourage conservation with aggressive fees for higher water use, said city engineer Klayton Eckles. "We are not worried about running out of water," Eckles said, "but you hate to go build million-dollar wells that are really only needed a couple days out of the year.''

Over half of the cities in the metro area have an odd-even system for summer sprinkling. While many homeowners think of that as a water conservation measure, Chris Elvrum of the Met Council said there is no evidence that it actually saves water, though "it does raise awareness of watering and conservation to a certain degree." The real purpose is to balance water use so cities don't have to expand water systems just to cope with an explosion of watering on the hottest day of the year.

The most delicate aquifer

Because aquifer levels vary from well to well, DNR officials say they cannot make sweeping judgments about whether water levels have dropped. But partly because of conservation laws passed after the 1988 drought, they have taken steps to protect resources they consider particularly sensitive.

Well drilling into the Mount Simon aquifer -- which is about 1,000 feet underground and holds water that is tens of thousands of years old -- is off limits unless cities have no other options.

But a water level survey reported that in 2008 in Scott County, Mount Simon water levels were the lowest ever recorded and had been dropping since 1980. According to Elvrum, it has dropped about 100 feet.

"While some of this is climatically induced, part of the decline must be attributed to pressures exerted on this aquifer by increasing development," the DNR report said.

One of the cities that draws water from the Mount Simon aquifer is Burnsville, where the city's 17 wells pierce three aquifers. DNR regulations require that three city wells near a protected wetland called Black Dog Fen be used only in an emergency.

Burnsville has taken steps to ease the demand on its wells and those in neighboring Savage: Soon, a new water treatment plant will turn between 2 million and 6 million gallons of water a day from a local quarrying operation into drinking water for both cities. For years the quarry has been dumping 10 million gallons of pristine groundwater into the Minnesota River daily.

Burnsville utilities superintendent Linda Mullen said Burnsville has enough water capacity to last another 20 years, but its odd-even watering schedule is only prudent. Residents seem to agree. Mullen said the city gets few complaints about water restrictions. In fact, she said, "people are getting on the conservation bandwagon.

"If we go through a dry period, we have people call and say, 'Hey, these people are sprinkling when they shouldn't.'"

Mary Jane Smetanka • 612-673-7380 Laurie Blake • 612-673-1711