Here's one that you may not have considered yet. It should do well in the site conditions at your location.

Here is a link that might be useful: Prairie Horizon Manchurian Alder

Thats a great suggestion! Let me know if you find a source corkball.

Autumn Splendor Buckeye is another good choice. Might be easier to find that one.

Interesting. I never considered alder. There are some natives up north but I always considered then junk trees. I should check on that. Thanks!

PS: already HAVE and Autumn Splendor Buckeye in the front yard, but thanks for the suggestion whaas!

whaas - Gertens in the Twin Cities has Prarie Horizon Alder - see link below

Here is a link that might be useful: Gertens plant catalog

River birch? (Betula nigra)?
Yellow birch (Betula alleghaniensis)?

Some sources say baldycypress will survive in Zone 4?

River birch? (Betula nigra)?
Yellow birch (Betula alleghaniensis)?

Some sources say baldycypress will survive in Zone 4?

It's like you people are in my HEAD! There is a river birch 20' away in the ditch, and I planted a baldcypress in the ditch as well (although I am hedging my bets here in case the cypress doesn't make it).

PS: also considering blue beech. Supposedly does well in heavy wet clay soil.

Half of the Bald Cypress I was aware of died in SE WI. Doesn't mean much except for I'd say they're borderline in the lower limits of zone 5.

I'n not sure why but Shawnee Brave seems to be more hardy. The folks that have them didn't have any dieback and the field stock in southwest WI and southeast WI didn't have any dieback either.

Larix laricina or tamarak or whatever they call it summer hardy in your area?

Since you liked metasequoia and taxodium. I am not an expert on the different larch's but my local botanical garden has at least one. Might be Larix decidua

Ash? (Although Emerald Ash border could be a problem).
Red Maple? (Acer rubrum).

Yes, blue beech (American hornbeam) does well in wet, low-lying heavy clay.

If you wanted to try something iffy off your list is the Tulip Trees seemed to fare the best after the last winter. Most of the Taxodium, Metasequoia and Nyssa I've seen up here were severely damaged of killed.

Thanks for all the suggestions:
1) ash - yeah I scratched that one off the list as EAB is getting REALLY close
2) Red maple - this is an excellent choice, but I already have several
3) I will TRY baldcypress, but again, don't want to rely on it making it
4) tuliptree - again iffy. and they can get REALLY big. I might try some up the hill away from the house
5) larch - yeah, that actually fits pretty well and would do well, but I have an inbred aversion to larch. No good reason - perhaps I am just speciesist!

What about a Catalpa? They often grown on sloped riverbanks and bloom with very pretty white little trumpet flowers..
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Have you seen the catalpa trees blooming? Most northern catalpas grow to heights of 60 feet, and in the late spring are filled with wonderful white blossoms. If youâÂÂve ever looked at one of the blossoms up close it resembles an orchid. Flowering takes place in late spring to early summer.

The flowers occur in large clusters of showy, bell shaped corollas of five lobes with ruffled edges and yellow, orange or purple interior spotting or streaking. Individual flowers are tubular shaped and measure as much as 1/2-inch across. They usually appear in clusters at the leaf tips and the clusters measure as much as 10 inches across. The flowers are good for honey production.

The name derives from the Catawba Native American name Catawba (the tribal totem).

The catalpa is a hardy deciduous tree that readily grows in USDA hardiness zones 4 to 8. It has moderate to fast growth, tending to grow rapidly when juvenile, but slowing with maturity. The height at 20 years is about 20 feet.

European settlers planted catalpa trees to produce fence posts. The wood is lightweight, and the heartwood is resistant to deterioration when placed in the ground for several years. Railroad companies grew plantations of catalpas for use as track ties and fuel wood. It was also used for making packing materials. Carpenters commonly used it for interior trim in houses. Craftsmen used it to make furniture.

Pioneer doctors used the seedpods and seeds to make a decoction for chronic bronchial affections, spasmodic asthma, breathing problems and heart problems. The juice from either the leaves or roots would be used to treat swelling of an eye, green leaves were crushed and placed on swollen lymph glands and the bark was dried and ground to powder and taken in the form of tea to treat swollen lymph glands. Modern pharmaceutical research has shown catalpa trees are diuretic.

It is sometimes planted to attract the green catalpa worms, which are prized fishing bait. The caterpillars can be frozen and used as bait at a later time.

Here is a link that might be useful: Catalpa - a showy, fast-growing ornamental tree

"The caterpillars can be frozen and used as bait at a later time."

When I was just a lad in the early '60's, I did this - but didn't tell my Mom. Imagine her surprise - and disgust.

yes my neighbor has one. I am not opposed to catalpa in theory, but they do get fairly big around here and messy and would rather not have one in that spot.
In my old neighborhood, they were planted as street trees, and while the flower show is very pretty, they drop their pods all over the place, and while not as bad as willow, they lose giant limbs and in some cases whole tops of the tree fall off.