A nasty, invasive plant might be blasted with herbicides in three Lake Minnetonka bays if a plan fashioned over eight months and talked about for years gets approval -- and funding.

The lake's homeowners group, the Lake Minnetonka Association (LMA), and the lake's official overseer, the Lake Minnetonka Conservation District (LMCD), have drafted a plan to kill off Eurasian water milfoil, beginning with a treatment of herbicides early this spring.

Those herbicides are meant to be selective -- reducing the amount of the nonnative milfoil, which forms dense canopies and annoys boaters, but leaving native plants.

"The trick will be the balance," said Dick Osgood, LMA executive director and a lake biologist.

The plan is based on the overall success of a 2006 test treatment in three bays -- Carman, Gray's and Phelps. All except Carman showed significant decreases in the amount of milfoil crowding the water.

This year's liquid herbicide applications could cost as much as $90,000 for Carman Bay, $70,000 for Gray's and $130,000 for Phelps, according to the draft plan. But no one is sure who would pay.

The LMA will likely apply for a grant from the Minnesota Department of Natural Resources to cover a small percentage of those costs. Then, lakefront-property owners would be asked to pay the rest -- voluntarily.

If 70 percent of property owners participated, they could pay as much as $1,400 each in 2008, with additional costs for maintenance treatments in future years, Osgood estimated.

The LMA will gauge interest among homeowners and begin a letter-writing, door-knocking campaign to collect funds. There's a tight deadline: To be effective, the herbicides must be applied when the water is still cold, in late April or early May.

As with street assessments, some lakeshore owners have questioned the idea that property owners should bear the cost of improving a resource many people use.

At a meeting this week, homeowners asked if people who own boat slips -- many of them in Gray's Bay -- would be considered property owners.

Richard Gay, who has lived on Carman Bay for 10 years, suggested that all boaters who use the lake should pay for milfoil treatments through an annual fee. "There needs to be some kind of equity," he said.

Chip Welling, coordinator of the water milfoil program for the Minnesota DNR, said boaters already do pay a fee, in a way. Because much of the DNR's revenue comes from a surcharge on boat registrations, "all boaters in the state are paying to do management," he said. "If you're putting your boat on, say, Lake of the Woods, you're paying for milfoil treatment on Lake Minnetonka." And while almost 200 Minnesota lakes have Eurasian water milfoil, the majority of them do not receive treatment funded by the DNR.

Access to Lake Minnetonka is free and should probably stay that way, Welling said. The LMA has at times promoted the idea of charging for access to the lake, proceeds from which would pay for projects on the lake. But the DNR and LMCD have insisted on open access.

The agencies have been battling milfoil for years. Since 1989, the LMCD has run a milfoil harvesting program. Each year, people on large floating harvesters spend the summer pulling mats of milfoil from 500 acres of the lake. This work would be suspended -- at least within the three bays -- if the treatment program occurred.

In addition, many homeowners get permits to apply chemicals to the lake close to their properties and do the work themselves or with contractors' help. Unlike the larger treatments proposed, those applications don't target particular plants.

"You clear everything," Osgood said.

In developing the management plan, the LMA and LMCD surveyed homeowners, business owners and others. They sent surveys to 755 people, 101 of whom responded.

About 44 percent of respondents said harvesting was only a "short-term, small-scale" solution to milfoil. About 66 percent said lakeshore owners' individual treatments were "OK as one element," and 17 percent said those treatments would not address the "larger problem."

About 74 percent of respondents said doing nothing in response to milfoil is "not an option."

Jenna Ross • 612-673-7168