De Soto ? A federal appeals court has dismissed claims by the Shawnee Tribe that it is rightful owner of the 9,065-acre former Sunflower Army Ammunition plant, clearing the way for the property to be privately developed into a residential and commercial area.

The 10th Circuit Court of Appeals in Denver ruled earlier this week that a decision last fall by Congress allowing the Army to get rid of the huge southwest Johnson County tract trumped the tribe’s claim to its historical reservation lands.

In a lawsuit filed in 2002, the tribe laid claim to the ammunition plant site and other Kansas land, citing treaties negotiated with the federal government in 1825, 1831 and 1854.

A federal judge ruled in late March that the tribe gave up rights to the land under the terms of an 1854 treaty under which the Shawnees ceded the future Sunflower site and nearly 1.6 million adjacent acres to the federal government.

The appeals court agreed. Records show the government paid $829,000 for the land, after which many of the tribal members moved to the Cherokee reservation in Oklahoma, where the tribe now has its headquarters.

In January, Sunflower Redevelopment LLC won formal approval to develop the land and clean up toxic waste at the former ammunition plant site. It’s estimated that the cleanup will cost about $200 million and take about eight years to finish.

The site previously had been targeted for a park and resort with a Wizard of Oz theme, but Johnson County commissioners rejected that plan in 2001.

Plans now call for light industry, residential development, green space and a research park on the property, which is in a prime growth corridor between Kansas City and Lawrence.

A still-pending lawsuit by a taxpayers group claims the government did not conduct a proper environmental assessment of the land, used for ammunition production from 1942 to 1989, and must do so before the land is transferred.

Officials expect the land transfer to Sunflower to be completed by the end of May.