Several things:
(1) I wouldn’t go overboard on the gutter/piping idea. The watershed from the condos to the pond appears to be clear. Water coming into a watershed will find its way to the pond whether you pipe it or not. The only thing that will prevent that is if the terrain has been altered so much that the water coming into the watershed has been diverted away from the pond. Putting gutters and piping in place will only make the same water come into the pond, but a little bit quicker after a rain. Not worth the expense.
(2) First thing I’d look for would be leakage. Don’t sweat any trees along the banks. The area you need to be concerned with is the backside of the dam. It needs to be completely clear of any vegetation except the grass that is in place to hold the dam together. Trees growing in the dam are the number one source of dam leaks. It’s not that the trees drink so much water, but rather that the tree roots provide a pathway for the water to escape the dam. Cut down any and all trees on the dam and remove their roots, filling in with good clay-rich soil. Be really careful in doing this if the pond is near full after a rain because your excavation of the roots will temporarily weaken the dam before you can back fill the area with clay. Also, have a good look at the spillway on either end, or sometimes both ends of the dam to make sure there’s no erosion there that would result in increased pond drainage.
(3) after doing (2) above I would look at purchasing some Bentonite to seal the dam from leakage. That will help seal up any leaks that were further aggravated by removing the tree roots. Bentonite swells enormously when wet. It is best applied when the dam is low and the Bentonite can be added in its dry form. Ideally you would be able to cut it into the dam with a disc and your tractor, but obviously that would only happen if the pond was dry. You can make that happen by removing the dirt from the spillway and allowing the pond to empty, then putting that dirt, plus Bentonite back in place once the Bentonite is cut into the dam. Then you can allow the pond to refill. Dint waste your money or time applying Bentonite over the entire pond. You only need to be concerned with the area in and around the dam.
(4) lastly I would contact the Agricultural Soil Conservation Service for them to visit the site and render their opinion on it. I put this last because the SCS used to be a lot of hands-on knowledgeable folks, but it has evolved into more paper pushers who prefer to stay behind their desks instead of working in the field. Not all of them, by a long shot, though. There are still those in the Service who prefer to get out and have direct contact with property owners, assess problems first hand and then develop action plans to remediate the situation.
In summary, I would focus on the backside of the dam first and not what’s going on in the front of the pond. Unless the water in the watershed has somehow been diverted, the water in the watershed will still find its way to the pond, regardless of how much you spend piping and guttering. The key here is to not waste money.