Adding a venue picture

I have received permission add a picture to my local library's venue page. The picture is a lovely watercolor painted by a local artist. The library owns the original and the rights. I can give credit to the artist, but I am unsure how to document the permission in the copyright section. Is there a standard way of doing this?

Just use "© name of copyright holder. Used with permission.". Put the year if you know it ("© 1990 name of copyright holder. Used with permission").

I assume this is a watercolor of the library?

Yes, it is a watercolor of the library. Thanks for the clarification.