Scattering cremated remains in a National park. This link is an entry point for the National Park Service information. The NPS site is difficult to get general scattering information.
One Week Road Trip to All 5 National Parks in Utah
One Week Road Trip Itinerary to all Five National Parks in Utah | The Needles District of Canyonlands | Hiking in Canyonlands & Arches National Park | Capitol Reef National Park | Bryce Canyon | Zion National Park & Angels Landing | The Narrows | Wooden Shoe Overlook and Big Spring Canyon | Pothole Point and the Cave Springs Trail | Hickman Bridge | Sunrise to Sunset hike | Mossy Cave Trail | It Started Outdoors