Scattering ashes at sea.
The federal Clean Water Act requires that cremated remains be scattered at least three nautical miles from land. If the scattering urn or 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. 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, lakes and ponds. For inland water burial, you may be legally required to obtain a permit from the state agency that manages the waterway. Burial at Sea - Code of Federal Regulations Click here