TAMPA — Mayor Bob Buckhorn once called the idea of filing an eminent domain lawsuit to secure a tiny piece of land for the $3 billion Water Street Tampa project "the least desirable option."

At this point, however, city officials have come to see it as the only option.

So this summer City Hall went to court over a parcel needed for a realigned and expanded road network in the mixed-used redevelopment launched by Tampa Bay Lightning owner Jeff Vinik and Bill Gates' Cascade Investment capital fund.

The land in question is small, less than a sixth of an acre. It sits between S Meridian Avenue and E Cumberland Avenue, which stops about 125 feet short of intersecting with Meridian.

Tampa officials have thought for years that it would make sense to extend Cumberland across the train tracks to connect with Meridian, and at least one other developer has worked on the idea. Now the Vinik-Cascade development company, Strategic Property Partners, wants to make that connection as part of its project around Amalie Arena.

The problem? The land is owned by the Tampa Hillsborough Expressway Authority and is part of a larger parcel leased to the ConAgra flour mill about two blocks to the north. A rail spur crossing the spot enables trains to shift cars from one train to another, a time-consuming process.

The lease is in place as long as the mill is in business, and it's not a small operation. Built in 1938, the 80,000-square-foot facility grinds wheat around the clock and ships 1.5 million pounds of flour a day to bakeries across Florida, the Southeast and the Caribbean.

Closing the gap between Cumberland and Meridian would create an east-west route through Water Street Tampa as well as a new connection from downtown to the Channel District.

But discussions with Ardent Mills, a joint venture between ConAgra and two other agri-business companies, have not produced an agreement.

"This has always been on the books from a transportation perspective," Buckhorn said last week. "We needed to do it 15 years ago, and now we're at a point where we can't wait any longer. This isn't something we take lightly, but it's something we have to do."

In addition to building a new section of Cumberland that would cross the tracks, the city also seeks to keep trains off the spur entirely from 6:30 to 9:30 a.m. and from 4 to 7 p.m. Monday through Friday.

The city also wants trains on the spur to observe local, state and federal laws regulating railroad operations at intersections with signals. That would mean complying with a city ordinance that bans trains from blocking many intersections for more than five minutes at times when there's a lot of traffic.

In its response to the lawsuit, Ardent Mills said the city's plan would effectively deny the mill the use of the property and do "severe damage" to its productivity, income and profits.

Nor, says the company, has anyone fully explained the extent to which the property would be taken, what would be built on it or whether there would be any limitations placed on its remaining property. Ardent Mills' attorney and corporate representatives declined to comment beyond the company's legal pleadings last week.

Strategic Property Partners (SPP) plans to build thousands of apartments, plus office towers and a million square feet of retail as part of Water Street Tampa.

First, however, the company is putting in new water, storm drainage and sewer lines, plus roads and other infrastructure.

The first $14 million phase of that infrastructure work started a year ago and is scheduled to wrap up in late September. The city and Hillsborough County have committed up to $100 million in downtown property taxes to reimburse SPP for the cost of improving streets, utility lines, sidewalks and other public infrastructure. The company can seek reimbursement once the improvements are done and accepted by the city.

A second phase costing $12 million is scheduled to start Sept. 18 and be complete in the summer of 2018. It is this phase in which SPP plans to close the gap between Cumberland and Channelside.

"If we had all the time in the world it might be different," top city development official Bob McDonaugh said last week, "but we're trying to complete these roadway improvements, and that's a part of them."

Contact Richard Danielson at rdanielson@tampabay.com or (813) 226-3403. Follow @Danielson_Times