Thanks, John and Jay for the feedback!
I should have been a bit more specific in my first post (I'm learning). Please see below for photos showing the well in its current form.
The previous owner already poured a concrete form around the spring itself as shown.
I think my question is - what should be done to cover and protect the wellhead from critters and other water overflows. As you can see - we have a little friend sunning himself at the moment. In its current form, the head of the well is covered with just some mesh, a plywood box, and some black plastic.
I'm very new to having a wellhead (especially with water so close to the surface) and am not sure what best practices are for keeping it clean, tidy, and drinkable.
Thank again.