Pine Springs is a micro-city east of St. Paul where hardly anyone lives — just 150 homes, with many on tiny lakes. Its household incomes are higher than Edina’s.

But its enviable lifestyle of sunset pontoon rides was threatened by the arrival of milfoil in 2008: Plants as tall as a three-story building turned all of Long Lake, the city’s largest, into a weed pond, preventing boating, water skiing and swimming.

Today that lake is pristine, but at a cost: $30,000 in the past four years from just 29 landowners.

In an era when many still believe that nothing can be done with invasive species, the quiet truth is that lake owners able to afford sophisticated scientific advice, and what one biologist calls the “phenomenal expense” of herbicide treatment, can succeed.

But a class system has arisen in which many landowners can’t or won’t take the same measures, raising a host of questions about whether the public should be stepping in to help.

In exurban Chisago County, officials are merely creating navigational channels through the mess.

On Big Marine Lake in northern Washington County, Mike Blehert, a property owner, said fewer than half of those owning shoreline are willing to contribute to a weed-control fund, pulling in only $3,000 to deal with a massive lake and limiting the range of solutions.

“To get a good-sized harvest machine,” he said, “you need to be Lake Minnetonka, with all those big mansions.”

But a number of people working in the field agree that big-buck lakeshore owners are also serving as an advance guard for the potential benefit of all by helping to finance cutting-edge research to establish the precise, targeted dosages and other details of how to vaporize unwanted invasives without ruining — and perhaps even enhancing — the surrounding environment.

Chip Welling, aquatic invasive species management coordinator for the Minnesota Department of Natural Resources, said there’s little doubt the wealth of an area plays a role in the invasive species fight.

Officials in the Valley Branch Watershed District, which includes Lake Elmo and Afton, and the Riley Purgatory Bluff Creek Watershed District, stretching along Lake Minnetonka and down through Chanhassen and Eden Prairie, are places that have “significant resources to bring to the table,” he said.

Long Lake today is in “fantastic” shape after having been 92 percent infested just a few years ago, said Matt Berg, of St. Croix Falls, Wis., who has examined 43 lakes in Minnesota and Wisconsin through his consulting firm, Endangered Resource Services.

Treatment is “phenomenally expensive,” he said, but people with means are having to ask themselves, “Are we going to have a lake to use at all, or a giant weed pond?”

“If you look at a house, it’s a valuable asset, and if the lake is so infested you can’t swim, ski or boat, you’ve degraded the value of your investment,” Brian Buchmayer, president of Friends of Long Lake, said as he gazed recently from his sloping lawn overlooking that small body of water.

Still, lake owners, however wealthy, draw no particular pleasure from having to self-fund cleanups that are often made necessary by outsiders who bring in invasive species with their boats, said Jon Early, president of the Tri-Lakes Improvement Association in Washington County.

“My opinion,” he said, “is that this is not a lakeshore owners’ problem. There would be no issue if lakes weren’t open to the public. Lake owners are already paying higher taxes for the right to live on the lake. On top of that, they’re being asked to pay for the weed problem. To me, that’s not right.”

Never-ending struggle

On the opposite end of the metro, Ellen Wells finds it more than a little ironic that she is having to pay crews every week to dive into the water to clear her beach of milfoil and create a weed-free zone so that her boat can make its way out onto Lake Minnetonka.

Her father, a retired 3M research scientist, gathered patents aimed at creating herbicides capable of targeting unwanted species under the challenging conditions of restless, moving currents, she said.

Today she seeks to sell her $3 million home on Spring Park Bay, a property advertised as nestled into an “unbelievable” setting along with “155 feet of pristine sandy level shore.”

Keeping it pristine, however, is a costly, never-ending struggle. One morning last week, half a dozen men with rakes labored up the property’s steep hillsides time and again with wheelbarrows. They were clearing the beach of 3 tons — literally — of Eurasian watermilfoil.

The crew cleared a ton the week before and planned to go back this week to do it again. On a single day, between jobs, the crew can remove as many as 20 tons of plant material, said Josh Leddy, of Life’s a Beach Shoreline Services.

Leddy is intrigued by plans to make use of all that plant material to create products with value to customers. But many others prefer nuking them with toxins and are eager for a time when regulations loosen.

The DNR’s Welling, and Becca Nash, associate director of the Minnesota Aquatic Invasive Species Research Center at the University of Minnesota, said steps are underway to gather the best research, often from wealthier clients of consulting firms, and deliver it to lake groups and others.

A U scientist, Welling said, is assembling data on success rates and detailed tactics to produce a “meta analysis that wouldn’t be the last word” but could be a giant step forward in distilling important information that “is not all being pulled into one place today.”

The research center, Nash said, has hired a plant specialist who starts Sept. 1 and will examine, not so much “promoting herbicide use, but at least how to get the most effect with the least impact on other things” and determine when to apply and how many times to apply “so it’s not just ‘dump and pray.’ ”

In the meantime, those who can afford to fight are growing impatient.

On Washington County’s McDonald Lake, ringed with million-dollar estates, invasive plants have mysteriously subsided, lakeshore owner Maynard Kelsey said.

The lake became so choked with weeds, he said, “somebody bought a weed puller — and got reported and fined.” Afterward, he said, there was a strong suspicion that someone was dumping illicit chemicals.

“A guy who did a weed survey claims it was surreptitious poison, and I’m guessing that’s the case because there was a decided reduction,” Kelsey said.

“Can’t prove it, no way to prove it,” he added. “But that’s what we think happened,” and on a lake where no such thing is currently allowed.