A lawsuit challenging the legality of the designation was filed in U.S. District Court in Portland in January 2006. The lawsuit was briefed over the next year and oral arguments were heard in April 2007. No decision has been issued.

Federal attorneys late last year notified the district that a Dec. 15, 2008, report from the Department of Interior's inspector general had concluded that then Interior deputy assistant secretary for Fish, Wildlife and Parks Julie MacDonald, acting alone or in concert with other Department of the Interior officials, took actions that potentially jeopardized the ESA decisional process in 13 of the 20 actions investigated. The bull trout critical habitat decision was among the 13 actions potentially influenced.

"As a result of this Investigative Report, Federal Defendants will be reviewing the decision and administrative record for this action to determine whether to continue this litigation, amend their litigation position, or pursue further administrative action with respect to the challenged rule," according to a federal notice filed with the court on Dec. 22.

After three months of deliberations, the agency opted to go back to the drawing board.

"Federal Defendants have concluded their review of the final designation of critical habitat for bull trout and, without any concession of law or fact, have determined that it is appropriate to seek a remand of the final rule," according to a federal brief filed Monday. Plaintiffs in the lawsuit are the Alliance for the Wild Rockies and Friends of the Swan.

The federal filing asked the court for 45 days "to pursue negotiations" with conservation groups regarding a timeline for completing the federal rulemaking process and producing a new critical habitat designation, which is defined by the ESA as specific geographic area(s) that contains features essential for the conservation of a threatened or endangered species.

"We will be taking another look at critical habitat" for bull trout, according to USFWS spokeswoman Joan Jewett. That will involve another complete run through the federal rulemaking process, which involves developing a proposal and an economic analysis of that proposal. It also includes public comment periods.

"They got what they asked for," Jewett said of the conservation groups' legal request to have the 2005 decision overturned and remanded to the USFWS.

The bull trout were listed as threatened under the ESA on June 10, 1998, and an initial critical habitat proposal emerged in November 2002 after prompting from a lawsuit filed in 2001.

"We've been waiting for seven years for that to happen," the alliance's Michael Garrity said of the prospect of a legal critical habitat designation. "We're delighted that the Fish and Wildlife Service decided not to defend the Bush Administration" decision.

The conservation groups favored the 2002 proposed designation of 18,671 stream miles and approximately 532,700 acres of lakes and reservoirs as critical habitat for the bull trout in the Columbia and Klamath basins. The proposal included large portions of main stem rivers like the Snake, Columbia, Clark Fork, as well as tributary rivers and streams throughout Oregon, Washington, Montana and Idaho.

But in a 2004 Columbia/Klamath final rule, the USFWS designated 1,748 miles of streams and 61,235 acres of lakes, about 10 percent of the critical habitat in the proposed rule. The agency said that it found, through public comment, that many areas originally proposed as critical habitat already had conservation efforts in place and did not need to be designated. In other areas, the agency said that the social and economic cost of a designation outweighed the conservation benefit.

A new final rule was ultimately published in September 2005 that combined critical habitat designations for the previously designated Columbia and Klamath stocks with the other three subpopulations, Jarbidge, Puget Sound, St. Mary's/Belly River, for which critical habitat had not previously been designated. The final designation was slightly larger than the 2004 final rule. With the additions, 3,828 miles of streams and 143,218 acres of lakes were designated.

The September decision prompted yet another lawsuit. The conservation groups asked the court to declare the 2005 final rule invalid and remand it to the USFWS. They also asked the court to order the USFWS to implement the 2002 draft rule as interim critical habitat for bull trout in the Columbia and Klamath, as well as all occupied habitat for the other three bull trout populations during the remand.

Bull trout are members of the char subgroup of the salmon family. They require cold, clean water to thrive and are indicators of water quality and stream health, according to the USFWS. Bull trout have declined due to habitat degradation and fragmentation, blockage of migratory corridors, poor water quality, past fisheries management and the introduction of non-native species such as brown, lake and brook trout. While bull trout occur over a large area, many of the populations are small and isolated from each other, making them more susceptible to local extinctions.

Bull trout have been found from their southern limits in the McCloud River in northern California and the Jarbidge River in Nevada to the headwaters of the Yukon River in Northwest Territories, Canada. To the west, bull trout range includes Puget Sound, various coastal rivers of British Columbia, Canada, and southeast Alaska. They are wide-spread throughout tributaries of the Columbia River basin, including its headwaters in Montana and Canada.

Bull trout also occur in the Klamath River basin of south-central Oregon. East of the Continental Divide, bull trout are found in the headwaters of the Saskatchewan River in Alberta and the MacKenzie River system in Alberta and British Columbia.