Would you leave your child in a body of water if you had the ways and means in which to remove him for a proper burial?
It is not the responsibility of the parents to locate their loved one. That burden falls to the responsibility of police and their search and rescue teams. Typically, no, always, when a MP is found, the police, and others in authority, will form a press conference or otherwise will make a public announcement so everyone can rest easier.
If your child were missing, when would you give up on finding them?
The police working this MP case will never give up on finding this young adult. Day after day of no success can become a daunting task. It will haunt them if they allow it. Even K9s get depressed if they are unable to locate the target for their trainer as they feel they failed at their job. Assuredly, Bryce is close in the thoughts of LE as they go about their work days.
The searches continue. They have utilized, thus far:
"Multiple search efforts have taken place since last fall, using "trained canines, watercraft, ground grid searches, drones and water sonar equipment"
The cost and trouble entailed on whether or not to drain a pond may be determined on whether or not the water sonar equipment detected the presence of Bryce. It may be drained in spite of it. I've been away from the thread for a while.