I'm glad this recurring question has arisen again.
About 3 weeks ago, our water had a distinctive "pondy" smell to it. It wasn't disgusting, but if you brought in somebody blindfolded and asked them where they were, they would know. A couple weeks later, the aroma mostly subsided.
This all occurred after a good dose of rain, so that may be a player...or not.
Does a pond with an algae bloom exude a "pondy" aroma?