First of all, a big welcome to Pond Boss.
If the stream doesn't naturally run into the the pond, even during relatively high water times, you might want to look at piping water from the stream into the pond.
Some good friends did just that on their farm to get above manure runoff that was getting into their 3/4 acre pond that is probably older than yours. They ran about 600 feet of 6-inch PVC that provided a head of several feet. Where it enters the pond they drop it from 6-inch to 4-inch with a ball-cock valve to regulate the water. They then run it through a vertical pipe that acts like a natural aerator for the incoming stream water. If they are getting too much water into the pond, they shut the ball cock valve.
Here is the pond as shown from the dam end. There is a driveway between the pond edge to the right, and a paddock. The stream is about 150 feet to the right of the driveway, and several feet below the level of the pond, as seen in the next photo.
The water intake for the pipe is through a filter in this area of the stream. The pond begins to the right of the red barn in the picture. There is a natural drop of 4-5 feet from this area of the stream to the pond.
The water comes into a small settling pond that we made. It now has a bunch of water plants growing in it to soak up nutrients before the water goes into the main pond.
Here is a close up view of the natural aeration caused by the water head from the stream.