Possible look to consider.

Pond before hardscape!

^^agree with Milly. The pond needs to come first.

why should the pond come first?

If there is a drainage problem, which you allude to with the trench, I'd resolve that first. Are you meaning to empty it into the pond? How will you filter the pond? Do you have electric there for a pump?

I suggest you measure the area involved then draw it out to scale.

Because you need to integrate the hardscape with the pond.

Hardscaping always comes first when redoing a landscape.......otherwise you will inevitably trash or seriously damage whatever you have undertaken before installing the hardscape.

And I would reconsider the planter boxes. There is nothing natural about them and they will detract from the overall natural effect you will want the pond to have.

IME as a professional landscape designer, designing and redoing a pond to have it function properly (as per Babs' advice) and look natural and well-intended for the siting is NOT a DYI project unless it is one that you have undertaken previously and with high success. I would get a designer involved sooner as opposed to later.

A version which includes hardscaping.

Thanks to everyone for your thorough replies!

@ NHBabs--
Over several months I've done a bit of research on putting a pond in. We're going for an all-year pond rather than a rain garden or seasonal mud hole (right now, that's what it is). I wanted to go with Bentonite since it's natural, but read too many complaints about leakage and murky water, plus just the two of us would have a hard time putting it in. I don't know anyone with hoofed animals that can tamp it either. It would be frustrating to put in clay just to have it leak for whatever reason, whereas you can potentially patch a liner. I'd love for clay to work though.

If we use a liner instead of clay, it would be a Firestone EPDM pond liner, on top of an underlayment and sand. The topmost ledge would be a large planting area with native species to assist with filtering, this would be 8-12" deep. This would be in addition to a solar-powered bubbler and barley straw.
https://getbusygardening.com/keeping-pond-water-clear-natural-way/
There would be another ledge 1' deeper, and the bottom of the pond would be 3'. We would also be submerging a siphon pipe in case of overflow from excess rain or if it ever needs drained.
http://www.georgialandsales.com/pdf/PondSiphonSystem.pdf

The previous owners put the wood flowerbed in. I'd love to have rock instead of wood for the flowerbed, not sure how I'd remove the wood without everything behind it collapsing?

@ emmarene--
The drainage issue comes from the runoff from roof of the carport behind the area. I don't want the runoff going into the pond. I'll be lengthening the trench to go downhill and away from the pond. I did draw up a plan with measurements and specifics, but don't have it scanned in right now. See above for filtering plan

@ gardengal--
We can't afford a professional designer and there aren't a lot of resources like that in our rural area. The supplies alone will be about all we can manage. Just going to have to do a heckuva lot of research...

We have a pond on the property I manage. It is surrounded by shrubs, native perennials and some groundcover. Also several types of grasses. My favorite plants in this landscape are the winterberry hollies and some of the decorative grasses. Also maidenhair fern and goatsbeard. Another plant that I would like to grow but have not had much success with is caryopteris. We also have golden twig dogwood and fragrant sumac and blue flag irises.

You can spend the winter digging. :)