A woman digging a sprinkler system discovered a grenade that police say may date back to World War II.

Grand Junction Police Bomb Squad Sgt. Stan Ancell said the grenade discovered Saturday was harmless because a detonating mechanism had been disabled.

Joann Martinez said her shovel pulled up the grenade and she briefly picked it up, then set it back down and covered it with a wheelbarrow before calling police.

Ancell said it appeared the grenade had been buried a long time.