Scattering ashes is generally legal, but there are many regulations of which mourners must be aware. There are different permits required to scatter ashes in different locations, reports Time.
The EPA mandates that ash scatterings occur at least 3 nautical miles from shore. They must be reported to the regional administrator of the EPA within 30 days of the scattering. Pet ashes are prohibited. Time reports that many states turn a "blind-eye" to ocean scatterings within the 3-mile limit but notes that this does not necessarily make it legal. Many national parks, such as the Grand Canyon, allow for scatterings with permission from the chief park ranger.