I installed surveillance equipment around our property and our pond. Mostly game made the footage, but there was one couple who came, partied, got naked, did their thing, and then left. And they left behind some trash (including used condom). I printed out some photos, posted down by the pond site where they were, and later footage show they returned weeks later, saw their pics and read my message, looked up and around and waved, got their stuff and left. Haven't returned since.
Obviously your pond is close to your home so ya aren't likely to have lovers enjoying your pond, but you might catch dumping of fish.
