Where can we store or scatter ashes after cremation?
In Idaho, there are no state laws controlling where you may keep or scatter ashes. Ashes may be stored in a crypt, niche, grave, or container at home. If you wish to scatter ashes, you have many options. Cremation renders ashes harmless, so there is no public health risk involved in scattering ashes. Use common sense and refrain from scattering ashes in places where they would be obvious to others.
Scattering ashes in an established scattering garden.
Many cemeteries provide gardens for scattering ashes. If you’re interested, ask the cemetery for more information.
Scattering ashes on private land.
You are allowed to scatter ashes on your own private property. If you want to scatter ashes on someone else’s private land, it’s wise to get permission from the landowner.
Scattering ashes on public land.
You may wish to check both city and county regulations and zoning rules before scattering ashes on local public land, such as in a city park. However, many people simply proceed as they wish, letting their best judgment be their guide.
Scattering ashes on federal land.
Officially, you should request permission before scattering ashes on federal land. As with local or state 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.
Scattering ashes at sea.
The federal Clean Water Act requires that cremated remains be scattered at least three nautical miles from land. If the container will not easily decompose, you must dispose of it separately. The EPA does not permit scattering at beaches or in wading pools by the sea. Finally, you must notify the EPA within 30 days of scattering ashes at sea.
The Clean Water Act also governs scattering in inland waters such as rivers or lakes. For inland water burial, you may be legally required to obtain a permit from the state agency that manages the waterway.
http://www.nolo.com/legal-encyclopedia/burial-cremation-laws-idaho.html