Thanks for the compliments. They were definitely a labor of love. We thought we'd be here longer to enjoy them and then sell, but plans change and when we ran the numbers we'd be stupid not to rent.
@bjornahland Yes, I am concerned with the up keep and having to deal with any possible mechanical or leakage issues. There is a pump filtration system for both. They are cleaned every few weeks in summer and we skim out leaves when necessary. Tadpoles and snails naturally do a good job of keeping algae to a minimum.
@gregm. Great questions. I hadn't considered permitting or insurance. I think the previous owner installed them himself so I would guess no permits were pulled.
After doing more research, at a minimum it looks like I'd need to fill the large pond to be no more than 18" since there is no fence and that seems to be a pretty standard requirement. Also, the large pond liner just started leaking. I am leaning toward filling the large pond and turning it into a planting bed and leaving the small front pond for curb appeal. If I did this I would include an amenities and structure addendum stating that amenities, e.g. the pond, could be rendered unusable at any time, so I could fill it if it became a hassle down the road. I would also include a filter cleaning schedule in the lease, much like you would for a pool.