Savanna Section

September precipitation at Mount Horeb WWTP, 9 km from Savanna Section, stands at 1.4 inches through mid-month, 0.8 inches below the normal of 2.19 inches for this date. Below-normal rainfall in August (3.5 inches, 0.4 inches below the 1901-2000 baseline) set conditions for the current water deficit.

A regal fritillary, a threatened prairie specialist butterfly, was observed on 2026-09-07 in Wisconsin. This striking orange and black butterfly requires intact tallgrass prairie habitat, which remains scarce in the Midwest. The species is among insects whose proposed federal protections are now delayed indefinitely, alongside the monarch.

Eastern purple coneflower was recorded in flower and fruit four times between August 25 and September 4, around Mount Horeb, Cross Plains, Verona and Monticello. This introduced species is now established across disturbed prairies and trail margins throughout the region in its typical late-summer window.

Wrinkleleaf goldenrod was in flower on September 16, with milkweeds and joe-pye weed at seed maturity. This autumn phenology unfolded during an unusually dry month with precipitation 0.8 inches below normal.

Mead's milkweed, a federally threatened species with range overlapping this area, has had no recent citizen observations. Habitat loss and fragmentation across the Midwest have reduced this rare prairie plant to isolated populations.

The ground under Savanna Section has flipped fast this summer. Weekly U.S. Drought Monitor reports for Iowa County held at zero percent abnormally dry for three straight weeks in July, the payoff of a wet stretch that finally reset the county after nearly ten months of some degree of dryness or drought stretching back to the previous October. Then, in the first week of August, 83.58 percent of the county jumped into abnormally dry classification, and it has stayed there, essentially unchanged, for three consecutive weekly reports since. Nothing has crossed into moderate drought yet, but the shift itself is the notable part: a full wet reset undone within about a week of the rain stopping. The same week last year the county sat at zero percent, so this year's dry snap has no analog from the prior season at this point in summer. What that classification does not tell us is whether anything on the ground has responded yet. The Drought Monitor is the only signal in the record here. There is no soil-moisture series for the county, no field observations logged since the shift, and a check of nearby USGS gauges returned no discharge readings for the period at all — so the honest position is that we know the classification moved and not much else. It is still worth watching, and it is worth being specific about where. Soil moisture is what governs seed-set in the tallgrass and the water moving through the smaller creeks and seeps that support aquatic insect emergence this time of year, which is why a late-summer swing can matter well before it registers as drought proper. Prairie plants with deep root systems — the kind that anchor this landscape's blazing-stars, prairie dock, and rosinweeds — are generally understood to buffer short dry spells better than shallow-rooted species, and the wetter microhabitats scattered through the savanna mosaic, seeps, sedge pockets, low swales, would be the first places to check for visible stress if it shows up. Whether any of that is underway right now is an open question, not a finding. The Driftless Area Land Conservancy works this stretch of southwestern Wisconsin, within the broader Driftless Area, and is worth knowing as one of the groups keeping an eye on how these landscapes hold up through swings like this one.

Glade Mallow (Napaea dioica) is in bloom here — two iNaturalist observations since late May, the most recent in late June, though both carry a quality grade of "needs_id" and have not yet been community-verified. It's a plant easily overlooked, its small white flowers rising above the taller coneflowers and grasses around it, but worth watching for. iNaturalist flags the species as threatened, and rightly so: it needs both male and female plants within pollinator range to reproduce, a challenge when prairie has been plowed or hydrologic conditions altered beyond recognition. Wisconsin holds some of the stronger remnant populations, and catching this species blooming here in its summer window is a quiet signal that the original savanna plant community is still rooted in this landscape. Its presence says something about what was here before.

American Bumble Bees have returned to the milkweed patches this month — a threatened species whose presence signals the pulse of a healthy pollinator community. Over thirty days, we've recorded seventy individual pollinator observations across the site, a surge that corresponds with the opening of the summer flowering sequence. Buttonbush unfurled its first flowers on July 9th, joining butterfly milkweed in a wave of nectar availability that marks the peak foraging window for native bees. Joe-pye weed is still budding but will follow within days. For many bee species, these three weeks are critical — the concentrated bloom period that sustains breeding and brood-rearing through the heat of midsummer. The ecosystem here is timed precisely to support them.

Stewart Lake carries an official designation now: impaired water that will require a cleanup plan under the Clean Water Act. The numerical breakdown is stark — nearly 70 percent of the surrounding watershed is devoted to hay and pasture or row crops, while less than one percent remains as wetland. That narrow margin matters enormously. Wisconsin's glacial lakes were shaped by a very different landscape. Centuries ago, wetlands rimmed these water bodies in dense abundance, filtering runoff and anchoring aquatic food webs before that water ever reached open lake. Systematic drainage — the tiling and dike-building of the 19th and 20th centuries — removed most of that buffer. What we see now is the ecological inheritance of that choice: runoff moves directly from agricultural land into open water, carrying nutrients that fuel algae blooms and degrade water quality. The impairment listing is not a surprise; it is the inevitable result of treating upland and aquatic systems as separate problems to be solved in isolation. Restoring this lake will require restoring connectivity — bringing back the wetlands, slowing the water, giving the land time to work.

Henslow's Sparrow (Ammodramus henslowii) held territory this June alongside Bobolinks and two declining checkerspots — Baltimore Checkerspot and Silvery Checkerspot — along with flowering prairie false indigo and wood lily. These species signal something rare: intact native prairie holding its ground in the Pecatonica watershed. The sparrow's presence is particularly striking — its population collapsed by 95% as fire-maintained grasslands were plowed under, leaving it nearly extirpated from the region. Dickcissel also recorded here. These birds depend on the open structure and native forb diversity that traditional Indigenous burning once sustained. This patch still carries that signature — evidence that long-term stewardship can slow and even reverse some losses, though the wider landscape remains fragmented and threatened by erosion. The East Branch itself still carries the burden of impairment, but the upland prairie quality here offers the river real refuge and recovery potential.