Manawa formed in reddish-brown silty clay loam lake-laid material that had a thin capping of silt, redeposited by the last advance of glacial ice. The till you're cutting into in your wettest mid-slope ground was first laid down as red clay in the basin of Lake Superior, carried south by water, and then reworked by the Lake Michigan Lobe. That's why the deeper horizons run reddish — it's not staining, it's Precambrian iron oxide riding the till.
In the Manawa series are nearly level or very gently sloping, loamy soils that are somewhat poorly drained. These soils are mostly in waterways in the eastern half of the county near the Kewaunee soils. They formed in reddish-brown silty clay loam lake-laid material that had a thin capping of silt. The lake-laid material had been redeposited by glacial ice. — Soil Survey of Ozaukee County, p. 23
Manawa silt loam, 1 to 3 percent slopes (MaA). — This is the only Manawa soil mapped in the county. Some areas are very gently sloping and are in waterways, and other areas are nearly level and are in the uplands. The areas generally are long and narrow or are roughly circular… The lower layers are clayey, and runoff is slow. As a result, the nearly level areas are slow to dry in spring and water is likely to stand in ponds on them in spring or after a heavy rain. — Soil Survey of Ozaukee County, p. 24
Included with this soil in mapping are small areas that have a surface layer of loam… areas that have a thicker surface layer than that in this soil because material washed from higher lying areas has accumulated on them… Other included small areas have a surface layer that is darker colored than that in this soil. Still other included small areas consist of very poorly drained Poygan silty clay loam. — Soil Survey of Ozaukee County, p. 24 · the source of the 10% hydric rating
The 1970 survey says it directly: Kewaunee soils make up about 70 percent of the association; Manawa soils about 15 percent; Poygan soils about 5 percent. If your property crosses an MaA polygon, you're almost certainly looking at the wet middle band of a three-zone slope sequence. Read the landscape, plant the right zone.
Well-drained reddish-brown silty clay loam till on the rises and side slopes. Dry-foot soils. This is your sugar maple, white oak, white pine, black cherry, hickory ground. Productive cropland historically.
Where you are. Mid-slope into upland waterways and shallow depressions. Water perches 1–3 ft down in spring. Trees here must tolerate seasonal saturation in the upper foot but handle summer drying once the table drops.
Very poorly drained, near-surface water table much of the year. Wet-feet species only — swamp white oak, silver maple, black ash (EAB caveat), tamarack, sedge meadow. This is the swamp/prairie restoration zone.
| Species | Status | Notes for MaA |
|---|---|---|
| Bur oakQuercus macrocarpa | nativeedge-tolerant | Not on the 1970 list but belongs on yours. Tolerates seasonal wet feet and the upland transition. Long-lived, fire-resistant, mast for wildlife. Best at the Manawa–Kewaunee boundary. |
| Swamp white oakQuercus bicolor | nativewet-tolerant | The defining MaA oak. Handles the saturation gradient from MaA into Poygan depressions. Mast crop. Plant on the wet end of your polygon. |
| White ashFraxinus americana | EAB — do not plant | On the 1970 list but emerald ash borer has functionally taken ash out of the planting palette in southeast Wisconsin. Skip. If you have surviving ash, monitor and treat for high-value specimens only. |
| Black ashFraxinus nigra | EAB — do not plant | Same EAB problem. Was the obligate wetland ash. Replace with swamp white oak or hackberry in your planning. |
| Red mapleAcer rubrum | nativewet-tolerant | Excellent MaA tree. Spring color, fall color, tolerates saturation. Fast-growing. Plant for canopy and aesthetic value. |
| BasswoodTilia americana | native | 1970 list. Best on the drier edge of MaA. Excellent pollinator tree — phenomenal nectar source for honeybees in late June. Pairs well with permaculture goals. |
| HackberryCeltis occidentalis | nativewet-tolerant | Not on the 1970 list but should be your white-ash replacement. Tough, urban-tolerant, handles wet and dry. Berries support overwintering birds. |
| CottonwoodPopulus deltoides | nativewet-tolerant | 1970 list. Fast nurse tree, but messy and short-lived (60–80 yr). Use as a temporary canopy while slow oaks establish, then thin. |
| Aspen, quakingPopulus tremuloides | native | 1970 list. Clonal — spreads aggressively. Consider only on the upland edge if you want a fast successional patch. |
| Weeping willowSalix babylonica | non-native ornamental | 1970 list. Skip in favor of native willows (black willow, sandbar willow) for ecological function. Reserve weeping willow for ornamental focal points only. |
| Paper birchBetula papyrifera | nativeheat-stressed | 1970 list. Climate change has made paper birch increasingly stressed in southeastern Wisconsin. Consider river birch instead. |
| River birchBetula nigra | nativewet-tolerant | Better climate-adapted birch for MaA. Exfoliating bark, lovely multistem form. Tolerates standing water in spring. |
| White sprucePicea glauca | native (north WI) | 1970 list. Native well north of you but plantable. Good windbreak conifer for the upland edge of MaA. Wet roots are a problem — keep off the depression. |
| Black sprucePicea mariana | native (bog) | 1970 list. Bog specialist. Only viable in the wettest, most acidic pockets. Probably not a fit for your specific MaA unless you have a true bog inclusion. |
| HemlockTsuga canadensis | nativemarginal here | 1970 list. Wants cool, moist, acidic, partial-shade conditions. Marginal on alkaline MaA. Skip. |
| Species | Status | Notes for MaA |
|---|---|---|
| Highbush cranberryViburnum trilobum | native | Top pick. Red fruit, fall color, wildlife magnet. Tolerates wet feet. |
| Gray dogwoodCornus racemosa | native | Thicket-former, excellent edge species, white berries for birds. |
| Silky dogwoodCornus amomum | nativewet-tolerant | Best dogwood for the wetter end. Blue fruit, strong streambank stabilizer. |
| Red-osier dogwoodCornus sericea | nativewet-tolerant | Red winter stems — stunning against snow. Spreads aggressively, give it room. |
| NannyberryViburnum lentago | native | Small tree or large shrub, edible blue-black fruit, fall color. Tolerates the moisture gradient well. |
| Wayfaring treeViburnum lantana | non-native | 1970 list but European. Substitute with native nannyberry or American highbush cranberry. |
| Raspberry · blackberryRubus spp. | native | Edible fruit, wildlife forage. Best on the drier upland edge. |
| Species | Status | Notes for MaA |
|---|---|---|
| TrumpetcreeperCampsis radicans | native | 1970 list. Hummingbird magnet. Vigorous — give it a sturdy trellis or trunk and prune. |
| Wild grapeVitis riparia | native | 1970 list. Native wildlife forage. Tame grape (cultivated V. vinifera hybrids) listed too — questionable for fruit on MaA per survey. |
| American bittersweetCelastrus scandens | native | NOT the invasive Oriental bittersweet (C. orbiculatus). Native is increasingly rare — worth planting for the orange-red winter berries. Verify source. |
| Species | Status | Why include |
|---|---|---|
| American hazelnutCorylus americana | native | Edible nuts, wildlife forage, thicket-forming understory. Drier edges. |
| Common elderberrySambucus canadensis | nativewet-tolerant | Edible flowers + fruit. Perfect for the wet edge of MaA. Cordials, syrups, jellies — straight-up Canvora-yard productivity. |
| NinebarkPhysocarpus opulifolius | native | Exfoliating bark, pollinator flowers, tough as nails. Tolerates wet and dry. |
| ButtonbushCephalanthus occidentalis | nativewet-tolerant | For the wettest pockets — bordering Poygan ground. Globe flowers, pollinator powerhouse, can stand in shallow water. |
| SpicebushLindera benzoin | native | Aromatic understory shrub, yellow spring flowers, swallowtail host. Likes moist part shade — Manawa understory is ideal. |
Because the subsoil and underlying material of the soils are compact, special care must be taken in locating a site and in designing a sewage disposal system. The dominant soils have moderate to severe limitations for use as filter fields. Basements commonly are wet because of seepage water. — 1970 Survey, Kewaunee-Manawa association, p. 3-4
The soils in this association have large volume change as the content of moisture increases. They also have low bearing capacity when wet. Use of the soils as sites for heavy buildings or for highways therefore is limited without major costs for foundations. — 1970 Survey, Kewaunee-Manawa association, p. 4
Translated to your property: any earthworks, foundations, septic, or paving on MaA ground needs frost-heave detailing, drain tile around footings, and probably a mound septic if conventional doesn't perc. For permaculture earthworks (swales, ponds), the clay subsoil is actually a benefit — natural pond sealing material, no liner needed.
Historic drainage districts. Ozaukee County has agricultural drainage districts on its heaviest MaA / Poygan / Pewamo ground, but they are concentrated in the Town and Village of Belgium in the northern end of the county. These are now consolidated as the Northern Ozaukee Farm Drainage District. Your property in Grafton (~43.32°N) sits ~12 miles south of that district boundary, so you are not in a regulated drainage district. That said, individual tile lines installed by previous landowners may still run through MaA polygons on private land throughout the county — worth probing if you see suspicious depressions, surface vents, or unusually dry strips during otherwise wet springs.
Wisconsin Wetland Inventory overlay. The 10% hydric rating on your MUKEY 425990 means some of that polygon may map as wetland under the WWI. To check the actual parcel:
dnr.wisconsin.gov/topic/surfacewater/swdv · zoom to parcel, enable "Wetlands and Wetland Indicators" layerWorking assumption: most of your MaA polygon is upland for regulatory purposes, but the low pockets (the 10% Poygan / Pewamo / Ashkum inclusions) almost certainly trigger WWI hits. Confirm before breaking ground anywhere near depressions.