SUN VALLEY — Idaho Gov. C.L. “Butch” Otter is challenging a federal decision to list a flower found in the desert of southwest Idaho under the Endangered Species Act, arguing that the government gave short shrift to conservation agreements worked out with local landowners.

Slickspot peppergrass, found in a handful of Idaho counties, is set to officially become a “threatened” species early next month following a U.S. Fish and Wildlife Service decision released in October.

But Otter on Monday filed a complaint in federal court alleging Fish and Wildlife relied on questionable data and completely ignored the work done by several state agencies, the Idaho National Guard, the U.S. Bureau of Land Management and local landowners and grazing permit holders. On Tuesday, he submitted a 60-day notice of intent to sue over violations of the Endangered Species Act, expanding on those complaints.

The notice now gives time for federal officials, including Interior Secretary Ken Salazar, to act on Otter’s concerns before the governor adds the ESA issues to his court complaint, said Tom Perry, legal counsel for the governor’s Office of Species Conservation.

Otter’s criticism of the data used to evaluate the plant relies heavily on a November 2006 letter in which Jeff Foss, state supervisor for Fish and Wildlife’s Idaho office, noted concerns with some of the data gathered by the Guard. Foss told the Times-News earlier this fall that an independent consultant reviewed all of the peppergrass data last year and found limited but statistically significant evidence for a decline in a Guard training area.

Perry, who spoke about the issue at the Idaho Cattle Association’s conference in Sun Valley on Tuesday, said state officials fear the listing will undermine any similar attempts at conservation agreements for species such as sage grouse — the subject of a Fish and Wildlife decision expected early next year.

“How do we invite these guys to come back to the table?” Perry asked.

The plant was originally proposed to be listed in 2003. But Fish and Wildlife changed its mind in 2005 after a challenge from the U.S. Air Force. The Hailey-based environmental group Western Watersheds Project then sued successfully to force the federal agency to reconsider.

All four members of Idaho’s congressional delegation immediately backed Otter on the issue.

Meanwhile, environmental groups seem confident that they’ll be able to help defend the move. Todd Tucci, an environmental lawyer in Boise, told the Idaho Statesman that he looks forward to persuading a judge “the governor doesn’t know the difference between real science and cowboy science.”