Are Public Land Fees Legal?

An interesting story out of Arizona could have some wide-ranging impacts on public-land agencies that charge fees for recreation.
In a ruling earlier this month, a U.S. magistrate in Tucson held that the U.S. Forest Service overstepped its authority by requiring hikers to pay a fee to park inside a national forest to access trailheads.
In the case at hand, Magistrate Charles Pyle dismissed two $30 tickets the Forest Service handed a Tucson woman for failing to pay a $5 fee on two different occasions when she went hiking on Mount Lemmon in the Mount Lemmon-Sabino Canyon area. You can find the details of the story here. In a nutshell, the magistrate said the Forest Service exceeded its authority by trying to charge folks a fee for simply being in a national forest outside of developed areas such as campgrounds.
What will be interesting is not just whether the Forest Service, which relies on the fees to help pay for maintenance and upkeep of campgrounds and picnic areas, among other things, appeals the ruling, but whether the ruling will prompt others to contest fees charged on other public lands, such as national parks and U.S. Bureau of Land Management properties.
Of course, a likely downside of this ruling is that the Forest Service will begin closing some campgrounds and picnic areas and other public-use facilities because it can't afford to operate them.
This is one of those slippery slope stories. If the ruling stands, and similar cases are successfully brought against the Park Service and BLM, these already cash-strapped agencies could lose substantial amounts of revenues and be forced to close facilities. Without congressional intervention, this could prove to be another example of the government starving the beast.