A proposed agreement to halt the pumping of groundwater from an Uptown luxury apartment building into the Minneapolis Chain of Lakes was outlined Monday afternoon in Hennepin County District Court.

The tentative agreement calls for Lake and Knox LLC, the owner of the 57-unit apartment at 1800 W. Lake St., to cease pumping groundwater by March 31, by which time it expects to have filled its lower parking level before letting it flood.

The building's pumps annually send 90 million gallons of groundwater to a nearby lagoon. That's enough to fill the seating area of Target Center.

The city of Minneapolis and the Park Board a year ago sued the building's owners, arguing that the groundwater pumping was both illegal and harmed the quality of nearby waters, particularly Lake Calhoun and the lagoon between Calhoun and Lake of the Isles. Judge Philip D. Bush ruled the pumping illegal on three different grounds.

The Park Board is not a party to the settlement, and its attorney, Brian Rice, is scheduled to discuss its litigation with the board in a closed session on Wednesday. It is seeking damages to offset the impact of extra algae-feeding phosphorus that city and park experts say is carried by the pumped water into the lake.

"We're very pleased with this settlement," Rice told Bush.

The general agreement hammered out by attorney Charles Nauen, representing the city, and Del Ehrich, for Lake and Knox, now will fleshed out. It's expected to be submitted to the City Council for approval in mid-January, and then submitted to Bush for formal approval.

"It appears this is a workable solution to a difficult solution," Bush said after hearing the tentative agreement.

The deal calls for the building owner to reimburse the city $130,709 for extra sewer cleaning and to reroute the pumped water from the lagoon out onto Calhoun to minimize unsafe ice conditions for the City of Lakes Loppet ski races. It will also pay about $75,000 more for rerouting the flow in the coming winter.

Lake and Knox said in court filings that it plans to use valet parking temporarily and build a new underground ramp next-door within a year to replace the parking it loses when the bottommost of two basement levels of parking in the building floods. That level was built below the water table; Lake and Knox is now seeking damages from several of its technical consultants on the apartment project, which was completed in 2011.

The replacement parking is outside the scope of the agreement, but Lake and Knox said it is crucial to replace parking to keep tenants and enough cash flow to finance the work. It plans to remove mechanical and electrical components from the lower parking level, fill it with sand and gravel and then seal it off from remaining basement parking. The firm said that work is crucial to ensuring the building remains stable. It estimates the work will cost about $1.2 million, while adding new parking is expected to cost about $2 million.

"This is a big construction project, lot of moving pieces. Everybody expects it will be implemented," said Ehrich.

"It is turning the basement into a much deeper footing for the building," Bush said. He'll keep jurisdiction over the implementation of the deal if disputes arise. Nauen said the deal contains a clause allowing for act of God delays.