Editor's note: This rewords the 15th paragraph to reflect that park officials did not say most comments received on the environmental assessment spoke in favor of above-the-rim rides over Inner Gorge rides.

The recent debate over mule rides in Grand Canyon National Park has left park officials, who say they have to live within their budgets and the public's desires, strongly criticized by mule backers, who say trail impacts might be less of an issue if park managers were smarter with how they spend their money.

Unfortunately for outsiders, fully understanding National Park Service budgeting is not always an easy task. There are funds dedicated to specific aspects of a park's operations, overlapping assignments that can make it difficult to tease out how much is spent on a specific area, and, among other things, funds that must be spent within a specific time-frame.

These challenges can be found in just about every one of the 394 units of the National Park System, which makes the following a helpful primer for those trying to understand how spending decisions sometimes are made in their favorite parks.

When Grand Canyon officials in March 2010 embarked on an environmental assessment to help chart the future of livestock use in the park, they pointed out that "an annual budget of approximately $3 million is needed to adequately maintain the park’s corridor trails; however, the park only receives between $1.5 and $2 million annually through entrance fees, concessions franchise fees and other sources for trail maintenance and repair."

"Additionally," they continued, "deferred maintenance costs on inner canyon corridor trails currently exceeds $24 million (GRCA PAMP 2006) – unless management actions are taken in the near future, trails will continue to fall into disrepair and deferred maintenance costs will continue to increase."

The uproar over the park's eventual decision to restrict public mule rides down to Phantom Range in the park's Inner Gorge to 10 mules per day along the Bright Angel Trail, and 10 a day from Phantom Ranch to the South Rim via the South Kaibab Trail, got me wondering about the trail maintenance funding woes, and how easily it might be to move money from another area to help meet those needs.

Since river trips down the Colorado River are a main attraction of the Grand Canyon and require more than a little attention from the park to manage, I figured that'd be a good place to look into the funding quagmire. What I found out is that nothing is entirely cut-and-dried when it comes to park funding.

For starters, Grand Canyon National Park currently spends about $1.4 million a year on river operations -- the permitting office, river patrols, concessions program, rangers staffing the put-in and takeout, environmental audits, and fee collections from river trips, just to name the most obvious tasks.

To cover that $1.4 million, the park receives a little more than $200,000 for river operations in its base funding from Congress, according to park spokeswoman Maureen Oltrogge. Another $600,000 or so comes from private user fees, she added, and the balance -- some $500,000 -- comes from concession fees.

“That pays for us to administer that operation," she said, "and that, too, pays for a ranger at Lee’s Ferry (the put-in), it pays for a ranger at Meadview (the takeout), it pays for river patrol operations."

And often those river patrols are multi-purpose, Ms. Oltrogge continued, explaining that while there might be a river ranger on the boat, there often might be someone working on Inner Gorge trail maintenance, vegetation studies, or archaeological or fisheries research. As a result, here can be a mingling of park funds traveling in that boat.

"It’s not as clean as you can take it from here without affecting something else. As nice as that would be, you just can’t do that," said Ms. Oltrogge.

Indeed, added Barclay Trimble, the Grand Canyon's deputy superintendent for business services, the money generated by river trips has to be spent on river management.

“All the stuff that comes from cost recovery from the privates (trips), that has to be spent on the resources that are being used to generate those fees. So that really can’t be reallocated at all," he said.

As to the furor over just 10 mule rides a day, park officials pointed out that current use patterns overwhelmingly show there are more hikers in the canyon than mule trips. Nearly 200 comments were received on the draft EA, they said in their synopsis, and "a wide variety of comments were received and a majority supported retention of at least some level of stock use in the park." By making more above-the-rim mule rides available, the park was responding to public demand, the officials said.

"I would say we're providing an opportunity for a bigger population, a bigger visitation base, to have that experience" of a mule ride atop the South or North rims, rather than in canyon's Inner Gorge, Mr. Trimble said during an earlier conversation. "We have had several comments over many, many, many years ... about a need for some above the rim. Not everybody wants to spend a full day going down into the canyon, baking in the sun, and coming back out.”

“The opportunity is still there, we are still providing mules down into Phantom Ranch and the North Rim is providing a ride down into the canyon," he added.

In an editorial endorsing the park's preferred livestock plan, the Arizona Daily Sun pointed to the disparity between the numbers of hikers and mule riders in the canyon.

In truth, it hasn't been the mule rides that have increased dramatically but the number of hikers -- hundreds of thousands now use the Bright Angel and South Kaibab trails each year. The two groups have combined to wear out the trails much faster than they can be repaired, resulting in a $20 million backlog of repairs.

But because there are no other viable trail corridors into Phantom Ranch, something had to give, and it was clear that the visitor experiences of 300,000 annual hikers were going to outweigh those of 10,000 mule riders. Deeply rutted trails filled with mule dung and urine, combined with rules of the road that give mule trains priority -- even when they step on a hiker's foot -- made it a foregone conclusion that some of the mules would have to go.

The move to fewer mules in the Grand Canyon is a changing of the recreational guard. While mules long have been associated with the canyon -- Brighty, anyone? -- the demand for mule rides into the canyon at a minimum seems to be slackening, while the influx of hikers determined to hoof it with their gear on their back is climbing.

Under today's budgeting scenario, something had to give, and park officials went into their deliberations with one certainty, as Ms. Oltrogge pointed out during our conversation.

“No matter what decision you make, you’re going to have people happy with it and people who are not," she said.