Native easy to direct sow plants for swales in clay soil in sierra foothills?

I am about to begin digging swales on my 12 acres in nevada county. We are out of the frost line but close to it in the foothills of the sierras. My property is sloped and the soil is very heavy clay so most of the water goes to the bottom of the land which has much more vegetation and bigger tree's.

I want to the help the oaks and other native plants at the top keep more of the water so I thought swales made sense. I am going to dig trapazoidal shaped ones above tree's and shrubs I want to get more water. I'd like to add some seeds to the swales that will continue to improve water penetration and soil health. The property is large so I do not have time to plant individual starts, I need something/s hardy I can cast.

Any ideas? It will recieve quite a lot of water in the winter and none in the summer. So I'm thinking something with deep roots thats drought resistant. Hoping to get them seeded now so they have the winter to establish.

Are you looking at perennials or annuals? Do they have to produce edible fruit/seed/leaf?
I'm further south from you and here is a short list of what grows neglected in full sun but in sady loam soil:
-sunflower
-fennel
-Swiss chard
Planting anything else from seed in the open slope always failed without exception.
From all the trees olives grow the best (no irrigation and produce fruits), but I never tried them from seed.
I have tried native plant (seedlings) but they also die, because they need an oak protection.
Sambucus cerulea grows very fast, is native, produces fruit, and is a riparian species, so there is a chance it would survive in clay swales. They did not like my slope though, but grows in the flat garden area. Burnt Ridge Nursery is selling them cheaply in bunches.
Figs would be worth trying, but again we are talking about the rooted cuttings not seeds.
Probably there may be more, but I'm only trying the edibles.

I would suggest native grasses: purple needlegrass, California fescue, Indian ricegrass, and California buffalograss.