"It was such a nice service for my deceased parent (or spouse, or other relative). Someday I just need to carry out their last request to have their cremated ashes spread on the lake." WAIT A MINUTE. Surely this can't be a practicing Catholic speaking! Even if the state does allow the scattering of a deceased one's cremains (which it does but only within certain guidelines and restrictions), it is not in accord with the Catholic faith. For those who desire to have their ashes sprinkled in a locale associated with one of their lifetime enjoyments such as gardening, visits to state parks, mountain climbing, etc., a reflection on the Church's teaching is in order.
Our Catechism (par. 2300) indicates that the burial of the dead is a corporal work of mercy and that it honors the children of God who are temples of the Holy Spirit. While the Church does permit cremation, provided that it is not done to demonstrate a denial of faith in the resurrection of the body, it also indicates in the Order of Christian Funerals (OCF) that "The Church clearly prefers and urges that the body of the deceased be present for the funeral rites". But then what is acceptable once the body is cremated?
The OCF states, "The practice of scattering cremated remains on the sea, from the air, or on the ground . . .is not the reverent disposition that the Church requires". Thus we need to honorably bury our deceased one's remains in a blessed grave plot, or entomb them in a mausoleum or columbarium specifically designated for cremains. Keeping them in a closet, under the bed, or on a mantel is not acceptable, since it demonstrates a lack of reverence, subjects them to accidental spillage or abuse, and places the burden on our heirs to provide their proper disposition once we pass from this world.
Realistically, none of us would try to have a deceased loved one's corpse sectioned and then those sections buried in various areas around the state or across the country because that person liked to travel and requested it be done. The same for cremains. The fact that they are in an easily transportable form doesn't free us from the obligation to make sure that they are properly buried.
Just as we are called to respect life in all its forms, so are we called to respect the remains of the dead. As the OCF indicates regarding the ashes of cremation, this respect "includes the use of a worthy vessel to contain the ashes, the manner in which they are carried, the care and attention to appropriate placement and transport, and the final disposition." Secular practices are not a substitute for the trusted guidance of the Catholic Church.