Since 2004 when the Federal Lands Recreation Enhancement Act (FLREA) was enacted, a park unit may keep 80 percent of recreation fee revenue collected. The remaining 20 percent goes into a centralized account for all NPS priorities. The FLREA money is allocated to certain projects tied to visitor experience.
I found interesting political history on fees on the NPS website. Concerning the proposed fee increase plan for the 17 NPS parks, Arches and Canyonlands included, the comment period is until Dec. 22. These proposals from the federal level are sensitive to public sentiment. Go to parkplanning.nps.gov/proposedpeakseasonfeerates for more information.
The Times-Independent website has the articles on this plan, with one written by Rose Egelhoff. The proposed plan might have been influenced by a U.S. Department of Interior revenue-generating audit of the NPS recreation fee program from 2015 by the Office of Inspector General.