How far from shore must a power water craft be if it is going faster than 5 mph?

In the US there is no universal set speed based on distance from shore. However, many areas have local restrictions which should be posted. The major concern is endangering swimmers or other boaters. Also, your boat's wake can cause problems for other boaters, swimmers, and damage the bank. Most places where speed is a concern have posted speeds from 4 to 7 knots, but again, regardless of speed, you must be aware of your wake.