Canyonlands National Park—which contains some of the planet’s most fantastic desert scenery and, paradoxically, two of the West’s mightiest rivers—just celebrated its 48th birthday.

The state of Utah is working to drive a knife into the heart of the park before it reaches 49.

The state and its ally, San Juan County, Utah, contend that Salt Creek, one of the few permanent streams in the park, is a “constructed highway” that the state—not the Park Service—can manage.

They plan to manage this stream not to protect its rich habitat for wildlife, but instead as a playground for Jeeps and SUVs, relying on a repealed, 19th Century law known as “R.S. 2477.”

This coming Wednesday, Utah will press its case in the Tenth Circuit Court of Appeals.

If they win, it will be bad news not just for this verdant canyon which is also a treasure trove of archeology (there are archeological sites inside the claimed roadbed).

That’s because Salt Creek is just the first domino the state hopes will fall to its extreme interpretation of law. Utah earlier this year filed 22 lawsuits aiming to take control of 10,000+ more “highways”—including streambeds, little used two-tracks and slot canyons—many in national parks, designated wilderness, or national monuments.

And there’s no doubting that the state’s legal theory is extreme.

The state’s lawyers have essentially asked the Court of Appeals to rule that any hiking trail or wagon track that was used by one or two people a few times over a 10-year period is a “constructed highway” that the state can control.

In essence, the state is hoping to turn a repealed, 140-year-old law meant to shield public investments in real higways into a sword to destroy wilderness.

By gaining control of such “highways,” the state could effectively tie the hands of park rangers and other land managers so they wouldn’t be able to protect the land, wildlife, or watersheds inside a national park from the destructive impacts of motor vehicle.

So a win for the state at Salt Creek could not only turn this quiet creek into drag strip, it could set precedent that would help the state in its bid in a score of other cases to transform millions of acres of the West’s wildest country into a spaghetti web of roads.

Fortunately, the state’s extreme arguments concerning Salt Creek failed to convince U.S. District Judge Bruce Jenkins, who ruled against the state in a lower court last year.

After the state appealed, the Southern Utah Wilderness Alliance, working with Earthjustice, filed a brief urging the Tenth Circuit to uphold Juge Jenkin’s decision.

Here’s hoping the Tenth Circuit has the common sense to back up Judge Jenkins, and to clamp the lid on Utah’s attempt to attack Canyonlands and other national parks, monuments, and wilderness across the state.