Even enjoying nature comes with a fee these days. And for Booz Allen Hamilton, the consulting company that helps run the recreational website people use to book campsites and permits for exploring public lands, those fees pay off big time.

Per documents filed with the government and viewed this week by the Wall Street Journal, the company invoiced the U.S. government for an estimated $140 million in incurred fees from October 2018 to November 2022.

The premise is simple — when adventurers apply for a parking permit, visitor’s pass, or book a campsite on Recreation.gov, they incur a small processing fee — a portion of which eventually makes its way to Booz Allen. The company also runs a call center for the government as well as an internal mobile app.

The news comes as Booz Allen is in its second year of a five-year contract. The original deal had estimated they’d receive roughly $182 million in fees over 10 years.

According to data obtained by WSJ, Recreation.gov saw around 10 million reservations in 2022, which was about 6.2 million more than the year prior.

A spike in outdoor activities brought on by the pandemic is thought to be the main factor in the uptick.

The government said that competing bids from other consulting companies were higher, the outlet noted.

A representative from Recreation.gov told Entrepreneur via email that the website uses a per-transaction contract model, something that has “been in place since the beginning” and noted that multiple vendors have “worked within that same contract framework.”