More than 200 Minnesota cities, from tiny Lauderdale to wealthy Rochester, will have to devise ways to keep the rain where it falls as part of a controversial new mandate designed to protect urban streams and lakes from the dirt and pollutants that wash off streets and yards along with the stormwater.

The cities, for the first time, will be required to maintain or reduce the volume of runoff leaving their systems, under a stormwater management plan approved Tuesday by the Minnesota Pollution Control Agency governing board. The plan also requires the cities to account for their share of pollutants such as phosphorus and sediment that foul many urban lakes and streams.

Although it’s been in the works for years, the proposal triggered fierce objections Tuesday from local officials, who say they are doing all they can to to improve water quality and that the new rules will add unknown millions of dollars in costs and responsibilities to cities that are already financially strapped and unable to ask residents for more fees.

“This is a huge undertaking,” said Nancy Burke, an attorney for the Minnesota League of Cities. Asking cities to control stormwater volume not just pollutants is “stepping way out into new territory for the state,” she said.

But after listening to hours of testimony, the board approved the plan unanimously, along with a promise by Commissioner John Link Stine to provide the cities with all the assistance and support possible.

“This is one of the questions of our time,” said board member Kathryn Draeger, a farmer and agronomist at the University of Minnesota. “How to balance declining resources with increasing pressure on our water resources.”

The new stormwater permitting process essentially requires each city to adopt the best way to hold water on the land techniques that could range from rain gardens to holding ponds to pervious pavements to new sediment-collecting baffles in storm sewers. The idea is to mimic the natural hydrology of each place in the most effective way to control pollution, the agency said. It can reduce phosphorus, a nutrient that causes explosions of green algae in lakes, by 90 percent, compared with the 50 percent that is typical of current water treatment systems, according to PCA officials.

That’s a sharp contrast to the way that most urban areas are designed today. Pavement, lawns, concrete driveways and rooftops are, for the most part, all designed to rush water off the surface and into sewers as fast as possible carrying dirt, chemicals, oils toxins, yard chemicals and nutrients that end up in lakes and streams, along with too much water that erodes banks.

Rapid runoff also robs groundwater and the aquifers that supply industry and most homes with drinking water, an increasingly urgent concern in Minnesota.

The mandate will apply to 234 cities and other government entities, such as watershed districts, colleges, the Minnesota Department of Transportation and the Metropolitan Airports Commission.

The first such stormwater permits were enacted in 2003 under federal pollution laws. The cities of Minneapolis and St. Paul are the only two in the state that are large enough to be regulated under a different permitting system.

But more than half of the state’s population lives in cities and municipalities that are affected by the new rules, the largest is Rochester.

“On the fundamental goals, to protect and improve water quality, there is complete agreement and always has been,” said Randy Neprash, an engineer for the Minnesota Cities Stormwater Coalition, an affiliate of the League of Minnesota Cities. But the cities object to several aspects of the rules.

For instance, each one will have to figure out how to regulate construction companies and developers so that they comply with the no new stormwater rule.

That means that if a new shopping mall is built on prairie, for instance, then the new mall has to replicate how the prairie handled water.

And redevelopments, such as a new shopping mall built on an old one, will have to actually reduce the volume of water that comes off the site.

Together, the new requirements “are huge” steps toward improving water quality, said Trevor Russell, program manager for Friends of the Mississippi River.

They will also require cities to manage the water coming off constructions sites, a significant contributor to sediment in lakes and rivers. Duane Duncanson, permit manager for the PCA, said that uncontrolled construction sites can release 30 to 40 tons of sediment per acre per year into surface waters.

Neprash, however, said the state is intruding too far into each city’s regulatory business, and requiring them to control water volume even when it doesn’t necessarily make sense.

The cities also objected to the potential costs. Each city will estimate its costs when it submits the water management plan that will be required starting later this year. PCA officials said that the new rules are designed to be flexible and designed to match the demands and capabilities of each city.

Richard Freese, Rochester’s director of public works, said estimates the new permit would cost each Rochester residents about $55 per year. And Rochester’s stormwater utility hasn’t had a rate increase in four years, he said.

Neprash said that cities aren’t trying to get out of managing their stormwater.

“They are just trying to find cheaper ways to do it,” he said.

Josephine Marcotty • 612-673-7394