The incident, prompted by legal action, will begin on March 21, according to a report posted today by KPHO News of Phoenix, AZ.
Western Horse Watchers was unable to find an announcement on the ASNF news page.
The horses will be drawn into the traps by bait.
The pre-gather population is thought to be around 400.
Delegates from the Salt River Wild Horse Darting Group will meet with Forest Service personnel later this week to discuss options.
The story did not indicate if the area was subject to permitted grazing.