National Forest System Trails Stewardship Act

Directs the Department of Agriculture (USDA) to publish a national strategy to significantly increase the role of volunteers and partners in trail maintenance.

Requires the strategy to: (1) augment and support the capabilities of federal employees to carry out or contribute to trail maintenance; (2) provide opportunities for volunteers and partners to carry out trail maintenance in each region of the Forest Service; (3) address the barriers to increased volunteerism and partnerships; (4) prioritize increased volunteerism and partnerships in those regions with the most severe trail maintenance needs, and where backlogs are jeopardizing access to national forest lands; and (5) aim to increase trail maintenance by volunteers and partners by 100% within 5 years.

Directs USDA to study opportunities to improve trail maintenance by addressing opportunities to use fire crews in trail maintenance activities.

Deems a volunteer with a partner organization to be considered a federal employee for the purposes of civil claims relating to damage to, or loss of, personal property of a volunteer incident to volunteer services.

Sets forth provisions for the selection of priority areas for increased trail maintenance accomplishments.

Directs USDA to establish a pilot program to offset all or part of the land use fee for outfitting and guiding permits.