LOUISVILLE, Ky. (AP) -- National Park Service officials are concerned that a company's plan to send natural gas liquids through an aging natural gas pipeline near Mammoth Cave National Park may pose a threat to the cave's ecological systems.

The proposal by Kinder Morgan to convert part of its Tennessee Gas Pipeline Co. operations has stirred controversy all year along a 256-mile path through Kentucky, The Courier-Journal reported (http://cjky.it/1JTLB0y).

Bobby Carson, chief of science and resource management for the park, said the 70-year-old pipeline may not be safe for carrying the liquids, which if spilled could damage the park's rare natural resources, including a variety of endangered species.

In a recent letter to federal energy regulators, park superintendent Sarah Craighead wrote that the Park Service "is concerned about the potential for a catastrophic failure of the ... pipeline" within areas designed to protect endangered cave shrimp and other rare park resources.

Kinder Morgan spokesman Richard Wheatley said the company is "committed to public safety, protection of the environment and operation of our facilities in compliance with all applicable rules and regulations."

Under the plan, natural gas liquids would be moved from fracking zones in Ohio and Pennsylvania more than 900 miles through a repurposed pipeline to Louisiana and Texas. That pipeline now brings natural gas to the Northeast.

Fracking is the process of removing gas or oil from rock formations by forcing liquids underground at high pressure.

While the Kentucky portion of the Kinder Morgan proposal does not pass through the national park, which gets more than half a million visitors a year, officials said they believe it comes close enough to potentially connect to the park's cave system and underground streams.