Scattering ashes on federal land may be an option. "Officially, you should request permission before scattering ashes on federal land. However, you will probably encounter no resistance if you conduct the scattering ceremony quietly and keep the ashes well away from trails, roads, facilities, and waterways. You can find guidelines for scattering ashes on the websites for some national parks. For more information, begin your search at the website of the National Park Service," advises nolo.com a public law website.