The National Park Service is delaying until late summer its proposal for dealing with a bloated elk population at western North Dakota's Theodore Roosevelt National Park.

The agency had said it expected to release a draft environmental statement with a "preferred alternative" for elk management by the end of February. Bill Whitworth, the park's chief of resource management, said the document's release has now been moved back to early August.

Whitworth said the process has taken longer than anticipated. He said the inclusion of a management option using volunteer shooters also factored into the delay.

Elk have multiplied rapidly in the park because they have few natural predators there and because hunting is not allowed. The animals' winter survival and reproduction rates also have been good.

The herd in Theodore Roosevelt's south unit has grown to as many as 900 animals, when the land can sustain only about 360.

Theodore Roosevelt park officials have been unable to ship elk out of the park because of nationwide restrictions prompted by worries about the spread of chronic wasting disease, even though CWD has never been documented in the park.

Park officials began considering the use of government and volunteer shooters only after pressure last year from U.S. senators and state wildlife officials in North Dakota and Colorado, where Rocky Mountain National Park also has elk overpopulation problems.

At one point, the North Dakota Game and Fish Department refused to participate in the new management plan process for Theodore Roosevelt National Park because of the dispute.

A public comment period of at least 60 days will follow the release of the draft environmental statement. Whitworth said a final record of decision on park elk management still could come by the end of the year, but the delay in the draft environmental statement could push it back into 2009.

Some ranchers who live around the park have been waiting for a decision, saying the elk cause problems when they escape the park's fenced boundaries. The Game and Fish Department is proposing more elk licenses in hunting units adjacent to the park, to help deal with the problem.

Gov. John Hoeven earlier this month called the park's elk overpopulation "essentially a federal problem that the state is stepping up to help fix." He met with National Park Service Deputy Director Dan Wenk in Washington, D.C., and discussed using qualified volunteers to help cull the herd.

Hoeven said after the meeting that Park Service officials planned a hearing in North Dakota.

Whitworth said this week that the hearing would be in conjunction with the public comment process after the release of the environmental statement, and not a special hearing beforehand.

Rocky Mountain National Park has wrapped up its elk management plan process. Its new plan includes the use of Park Service employees and volunteers to cull the herd, along with other measures including birth control for some female elk.

South Dakota's Wind Cave National Park also has a documented elk overpopulation problem and is working on a new management plan. Its draft environmental statement is on track to be released in April or May, Park Superintendent Vidal Davila said.