Prior Lake, the most important recreational lake in the south metro area, is so heavily used that it was one of the first in the Twin Cities to be infected with razor-sharp zebra mussels. Its shoreline is so sensitive that after rains, boaters are warned to reduce speeds to minimize erosion. It's already on an EPA list of impaired waters.

So when a marina business proposed to double the length of its dock to the span of two football fields, sending it far out into a small bay, outraged lake homeowners jammed City Council chambers to protest.

They scored a victory recently when the owner of Waters Edge Marina withdrew his plan. But the conflict exposed the prickly relationship between private and public lake users as the lake gets more crowded and environmental issues get more sensitive. It mirrors the kind of friction that has cropped up in other areas, such as Lake Minnetonka.

"It's not their lake," Zack Reimers, whose Prior Lake home is near the bay, said of public users. "They just come out to use it for a few hours, and they couldn't care less who they tick off."

The set-to also left Prior Lake officials scrambling to determine how heavily they should be involved in regulating the lake.

"I've got more questions than answers," said Jeff Phelan, head of Prior Lake's Planning Commission, which tabled the marina's proposal after a three-hour meeting to review it and get public feedback. Among the unknowns: a clear definition of what qualifies as a commercial marina in Prior Lake.

Those questions still need to be answered even though Waters Edge owner Dan Schmid withdrew his proposal one week after the meeting, said Community & Economic Development Director Dan Rogness.

"We'll need to sort through what should be the basis for someone getting commercial marina docks. There's guidance but not specific criteria. Whether someone's proposing 50, 60 or 100 boat slips, what's the proper number?" Rogness said.

Schmid declined interview requests and did not tell the city why he withdrew his plan, Rogness said. Schmid's family business has owned the marina on Boudin's Bay for three years and in 2011 rankled neighbors when it expanded from 25 to 50 boat slips. The latest expansion would have added another 46.

"Nobody likes that being there," Reimers said at the meeting. Reimers said the current marina already puts too much boat traffic on the bay on Lower Prior Lake and adds to pollution problems like petroleum products from motorized watercraft.

Homeowners told the commission the congestion is so bad they don't take their boats out on weekends, and that some marina boaters steer too close to homeowners' docks and the shoreline — an environmental and safety hazard. The outsiders sometimes ignore "no-wake" rules, they said, churning up phosphorous from sediment in the shallow bay, which prompts the growth of algae.

Upper Prior Lake, which flows into Lower Prior Lake, is already on the EPA's list of impaired water bodies because of high nutrient levels that impair aquatic recreation.

Homeowners at the meeting also expressed their sense of entitlement to the lake, which they share with public marinas, swimming beaches and boat access points. "I pay good taxes to enjoy this lake," one angry homeowner told the commission.

Adding to residents' frustration are city rules that peg the number of boat slips for lake homeowners' associations to the amount of shoreline they own. One association has 20 homeowners on its waiting list for a slip. The city has no such rules for commercial marinas.

But some individual homeowners also may be contributing to congestion problems on Prior Lake by adding slips not for their own use, but to rent out. The city has no ordinance for single-family homeowners, relying on a "a good neighbor policy" allowing up to six boat slips per house, Rogness said.

"It causes issues with the neighbors," said Donna Mankowski, an officer of a homeowners association and former member of the city's lakes advisory committee. "You've got people walking in and out of yards, cars sitting out in front of residential properties." Mankowski said it further illustrates a need for tighter dock ordinances.

Boat slip permits for all marina businesses used to be handled by the Minnesota Department of Natural Resources. But the DNR changed its rules and now only handles permits for commercial marinas that provide ancillary services, such as food or gas, which Waters Edge doesn't offer.

Reimers said he thinks it's possible some homeowners associations may look into Schmid's 2011 expansion "to make sure that the permits were legit." The DNR handled that request as an amendment to the marina's original 1989 permit, said Jennie Skancke, south metro area hydrologist for the DNR.

"The city didn't do its homework this time," Mankowski said of the conflict stirred up by Schmid's expansion proposal. "Now we know there's an issue. Let's get it fixed now."