The largest outdoor arts festival in North America is about to become bigger.

Federal land managers have issued Burning Man organizers a four-year special recreation permit that allows a peak population of 68,000 on the northern Nevada desert this year.

Last year, attendance at the offbeat art and music festival on the Black Rock Desert peaked at 56,000 — below the previous maximum allowable population of 60,900.

The festival will be held Aug. 26-Sept. 2.

Gene Seidlitz, manager of the U.S. Bureau of Land Management's Winnemucca District, said the agency is requiring organizers to comply with more than 60 conditions related to issues such as security, public safety, resource management and cleanup.

He said he's confident that sufficient requirements are in place to protect the starkly beautiful desert's environment and to ensure public safety.

"Our priorities in managing this permit continue to be the protection and conservation of natural and cultural resources, as well as the safety for all participants and staffs," Seidlitz said. "I feel confident the permit addresses these priorities."

Burning Man spokeswoman Megan Miller hailed the BLM's issuance of the multi-year permit, saying organizers are establishing the first shuttle bus service to the event and making other improvements to Black Rock City's infrastructure to prepare for larger crowds.

During the annual weeklong event leading up to Labor Day, the temporary city on the desert about 100 miles north of Reno is one of Nevada's largest.

"We have always been confident in our ability to grow the event safely and sustainably and have been asking the BLM for this increase for several years," Miller said by email. "We have always had a safe and engaging event and look forward to another great event on the playa this year."

The gathering, which draws people from around the world, is the largest permitted event on federal land in the United States.

After it moved from San Francisco's Baker Beach, the inaugural Burning Man in Nevada drew some 80 people in 1990. The first 1,000-plus crowd was in 1993, and attendance doubled each of the next three years before reaching 23,000 in 1999. The crowd was capped at 50,000 under a five-year permit that expired in 2010. The new multi-year permit allows a maximum crowd of 70,000, but organizers applied for a cap of 68,000 this year.

The BLM issued a notice of non-compliance to organizers for exceeding the attendance cap of 50,000 at the 2011 festival, which drew crowds of more than 53,000 on two different days. It was the first time Burning Man had been placed on probation since moving to Nevada. The BLM had warned that if organizers were placed on probation two straight years, the agency might suspend or cancel their permit.

"It's important to note that we may not reach the maximum allowable population (this year)," Miller said. "We don't want to exceed the maximum so we are planning accordingly."

Seidlitz praised organizers' overall efforts in meeting terms and conditions of past permits.

Organizers have always met stringent cleanup standards, he said, adding that the gathering pumps millions into Nevada's economy.