Where do you live?

Ave you contacted the city? county? local power agency?

It looks like an electrical box/system for some electrical purpose. Even though PVC is used, I see nothing water-related.

Maybe it used to be an electrical outlet, and they discontinued using it. The easiest solution is just to put a blank cover on the front, shutting off access to it.

Agreed. It may still be 'live' and if it's outside, I'm wondering if it has a ground fault interruptor. Probably used for fountain or lights, or even electric weed eater or lawn mower. If you don't plan on using it, you may want to check your entrance box and disconnect that particular circuit, or at least make sure the switch is off.

an electrician can trace it back for you ...

as well as a screwdriver.. to take off the cover.. AND LOOK ...

ken

That's why I suspect it's electrical. Hardware stores are full of the dummy covers like this one has where someone is covering up an unused electrical box. I have seen so many situations where people just take the easy (but not necessarily safe) way out and would not assume just because a box has a dummy cover on it, it's not live.

If they had the sense to fill in the list inside the door of the breaker panel, you might be able to find which breaker controls it, and it may even say what it was used for.

Definitely don't touch any bare wires without confirming that it's off using a meter or test indicator lamp.