Goethermal energy development plans for an area adjacent to Yellowstone National Park might destroy or seriously damage the worl-famous geysers, steaming hot springs and boiling mud pots in the country's largest and best-known park, federal officials here say.

Under the proposal, which is causing controversy and concern, more than 70 energy companies and individuals would drill deep wells in the forested Island Park geothermal area southwest of the park to generate electrical power.

The plan is under consideration by the Forest Service and the Bureau of Land Management, which administer the 5000,000-acre area astride the continental divide in Wyoming, Montana and Idaho.

The eastern boundary of the proposed development area in Targhee National Forest is 13 miles from the renowned Old Faithful Geyser in Yellowstone, and Island Park is home to the endangered bald eagle and peregrine falcon and the once-threatened trumpeter swan.

Other considerations that could affect the success of the proposal for 200 leases include the Environmental Protection Agency's assenment that geothermal development may adversely fffect water and air quality in the area.

However, it is the possibility that the hydrothermal features of Yellowstone and Island Park may be connected that concerns Interior Department officials and and environmentalist who have become increasingly worried about energy and other development encroaching upon western national parks.

Both John Townsley, superintendant of Yellowstone, and Glen T. bean, regional director of the National Park Service here, have criticized the plan to the earth's natural heat near Yellowstone, the birthplace in 1872 of the national park concept.

"We believe there is a real possibility that the proposed utilization of geothermal resources west of Yellowstone National Park would seriously impair or destroy the principal resource of the park", the officials wrote May 11 in a letter to Dr. William P. Gregg, chief of the Office of Environmental Compliance for the National Park Service

William J. Whalen, director of the park service, which has recommended that noe leasings occur without further study of possible detrimental effects to Yellowstone, said the threat "has broad international significance." "When you say 'park' in America, Yellowstone is the first one that come to mind. When a threat comes to a place like Yellowstone, you're going to find everybody in this country standing up to it," Whalen said.

But a little-circulated draft environmental impact statement by the Forest Service and the BLM drew a majority of comments favoring the leasing proposal, which has surprised and alarmed conservationists, many of whom learned of it only recently.

"There is concern that if they are in the vicinity of the park, the next step could be to attempt to breach the park", Clifton Merrit, executive director of the Denver-based American Wilderness Alliance, said of the energy developers.

Voicing concern shared by other major environmental groups, Merrit said the leases, which could be granted under the Geothermal Act of 1970 permitting geothermal development on public land, should be banned.

"We need to develop all reasonable energy sources, but there are some that we just have to forgo, and those are our park units if we want to have national parks worthy of the name," he said.

The proposed developments, even through it would be outside the park, still could affect Yellowstone, which is downwind, the EPA said in formal comments on the proposal. The plan could cause ozone pollution and acid rain -- sulfur dioxide emmisions that undergo chemical changes and combine with water in the atmosphere, the agency said.

But if the cheif environmental concern is that drilling 10,000-foot-deep wells in Island Park could effect the fragile plumbing of Yellowstone, project proponents such as the Occidental Petroleum Co., which wants to develop 1,000 acres believe that the risk is small.

"The thought is almost ludicrous," Malcolm Mossman of Occidental's Bakersfield, Calif., office said of the belief that the hydrothermal features of Island Park and Yellowstone may be connected.

It is known whether such a connection exists. Nor is it known whether geothermal energy can be commercially developed here.

Proponents of the proposal say geothermal is a clean energy source needed by a nation caught in an increasing energy squeeze. "We cannot set aside all land in the face of progress," said Denver relator S. Paul Wasserstein, a leasing applicant.

"Tthe beauty of Yellowstone Park cannot be allowed tto influence the development of alternative sources of power in other geothermal fields of our country. Why let our emotions restrict development of an energy source outside the park . . . ?"

But nothing the destruction of geyser fields in Nevada and New Zealand because of adjacent geothermal development, the interior Department is taking a cautious approach toward the proposal.

"Any man-caused threat to the integrity of its [Yellowstone's] thermal resources is totally unacceptable both nationally and internationally," the department said in comments about the proposal.

The department has outlined a monitoring program to check on any connections between Island Park development and geothermal features in Yellowstone should leases be granted. But some National Park Service officials such as Gregg are skeptical about whether such a program could detect early man-mande damage to the park.

The final environmental impact statement should be completed by Oct. 1, along with the Forest Service's recommendations on leasing in Island Park. Interior Secretary Cecil D. Andrus must give final approval. %00:1500000120: CAPTION: Map, no caption, By Dave Cook -- The Washington Post