Green Bay's Lake Michigan water is 130 mg/L hard, enough to mark glass as it dries, and fine paper-mill particulate drifts along the Fox River corridor.
Green Bay's Lake Michigan water sits just over the line into hard, which the utility itself describes as the middle of the range, so expect light deposits wherever rinse water dries. Fine paper-mill particulate drifts along the Fox River corridor, and July to September is the dependable window. Large glazed homes on the east side and in Bay Settlement price at the top of the range, while a single-story exterior runs $240 to $430.
At a published 130 mg/L the supply is just over the line into hard water, and the utility is unusually frank about it — its own framing is that Green Bay has neither soft nor hard water but sits in the middle. For glass that means deposits on evaporation and nothing worse. There is no etching risk at this concentration and no case for a deionised system on residential work; there is a strong case for never letting a pane air-dry.
| Hardness | 130 mg/L as CaCO₃ Hard, as published by Green Bay Water Utility. |
|---|---|
| pH | 8 |
| Manganese | 0.00053 mg/L |
| Sodium | 8.9 mg/L (range 8.6–9.1) |
| Chloride | 16 mg/L (range 15–16) |
| Total dissolved solids | 150 mg/L |
| Disinfectant | ozone + chlorine |
| Source and treatment | Surface water, per the EPA SDWIS federal record · Coagulation and pre-chlorination, rapid mix, flocculation, sedimentation and rapid sand filtration, pre-ozonation and post-chlorination, and fluoridation · No softening step. |
Not in the report: alkalinity, corrosion index and iron.
SOURCE · Green Bay Water Utility 2025 Annual Water Report, with the EPA SDWIS federal treatment record, PWS WI4050356 · How we source these numbers
Mineral marking is a constant, because the supply does not move seasonally. Organic load is what changes: tree pollen through spring, grass into early summer, then ragweed from August until frost ends it. Mill particulate along the river runs year-round and is worst in dry, still conditions. The clean window that holds longest is late spring; the shortest-lived wash of the year is one done in early autumn.
WISCONSIN SEASON BY SEASON →Green Bay is a city where the water is the easy variable and the calendar is the hard one. The utility publishes a steady 130 mg/L drawn from Lake Michigan through a Kewaunee intake, and because that figure barely moves across the year, a crew can settle on one rinse routine and stop thinking about it. What actually governs work here is the season: exterior washing is genuinely off the table through the coldest stretch, freeze-thaw punishes any water left in a glazing bead on the older stock, and the demand that would otherwise spread across twelve months compresses into the open ones. The best-value residential wash is late spring, after tree pollen has finished and before the ragweed season that runs August into October. The worst is a September wash that buys three good weeks. Layer the Fox River mill particulate on top of that and the honest advice is an interval on the commercial frontage and a season on the houses.
Green Bay does not drink the bay it is named after. The utility's supply is drawn from Lake Michigan proper through an intake off the Kewaunee shoreline and piped west to the city, which is why the water arriving at a tap here behaves like open-lake water rather than like the shallow, nutrient-heavy water of the bay a few blocks away.
The utility answers the hardness question directly and publishes the number: 130 mg/L, which it puts at roughly 7.5 grains per gallon. It also says what most operators leave out — that hardness is checked weekly in its own laboratory, and that the lake runs consistently at that figure give or take a handful of milligrams, typically landing between 125 and 135.
That consistency is the operationally useful part, and it is rarer than it sounds. A river-fed or well-fed supply moves with rainfall and season, so a crew calibrates to an average and gets caught out twice a year. Here the number a crew plans against in February is the number it gets in August, which means a rinse routine that works once works all year.
At 130 mg/L the supply sits just inside the hard band rather than the moderate one, and the practical threshold that matters is not the band label but evaporation. Water at this concentration leaves a visible deposit if it is allowed to dry on glass, and does not if it is pulled off. The whole method here reduces to finishing every pane to a dry edge instead of trusting the air.
The Fox River corridor carries the heaviest concentration of paper manufacturing in the state, and the mills are inside the city rather than outside it. Glass on the downwind side of that corridor picks up a fine particulate load that behaves differently from ordinary road grime — it is light, it bonds when it gets damp, and it rewards a genuine wash over a wipe-over.
Winter here is long enough to change the shape of the trade rather than just pause it. The city holds below freezing for extended stretches from December into March, which rules out exterior washing for a real part of the year and compresses residential demand into a shorter season than the calendar suggests. Local crews carry interior and commercial work through the cold months for that reason.
Freeze-thaw is the other half of that, and it is the failure mode that costs a homeowner money rather than a crew time. Water driven into a failing glazing bead during a thaw and frozen that night is what opens the bead, and a wash is exactly the event that introduces the water. On the Astor and Olde North East stock that is a reason to work dry days with a dry-down window, not merely a reason to work warm ones.
Pane count drives the top of the range on the newer east-side and Bay Settlement stock, where glazing areas are large. Access drives it in the older districts, where ground is uneven and sash are divided. Route density is what keeps residential pricing tight, because Allouez and De Pere sit on the same run and a crew that fills a day inside that territory can price a single house more keenly than travel time alone would allow.
Single-storey post-war stock on the east and west sides is reasonable homeowner work, provided the panes are finished to a dry edge rather than left to evaporate. The Astor Historic District is not beginner work at any storey — old putty and original glass punish a scraper — and the Broadway District shopfronts are a frequency contract rather than a one-off job.
OPEN COST ESTIMATOR →2025 annual mean at the Green BAY East High monitor, East High, 1415 E. Walnut, 1.7 km south of the city (EPA site 55-009-0005).
Largest air release: Georgia-Pacific Broadway LLC, 1919 S Broadway (paper), inside the city limits, 18,647 lb in 2024.
When the Green Bay Water Utility has run the city wells 12 hours a day for four days straight, the mayor may declare water restrictions: no noncommercial lawn and garden sprinkling, no car washing and no flushing of driveways.
Green Bay Code §42-69: water use restrictions · checked September 2026
Green Bay bars anyone from throwing, draining or discharging pollutants, or water carrying them, into the city's storm sewer system, or letting others under their control do it. Only listed clean flows, such as water line flushing and landscape irrigation, are allowed.
Green Bay Code §16-111: illicit discharges or connections · checked September 2026
No owner of a Green Bay historic site or structure, or of a property inside a historic district, may construct or alter any part of it, and no building permit is issued, until design review is finished and a certificate of appropriateness has been issued.
Green Bay Zoning Code §44-1553: review of construction, reconstruction, or alteration · checked September 2026
Lake-effect snow loading on east-facing roof systems produces heavier ice-dam runoff than interior Wisconsin. Same chemistry and protocol Linnea Jorgensen documents for the Twin Cities: percarbonate prerinse, citric acid lift, attention to dwell times.
Milwaukee-specific. Neutralized iron-and-manganese leach plus cream-brick clay constituents stain glass below cream-city brick courses with a yellow-brown deposit pattern not documented elsewhere. Oxalic acid handling required; citric alone underperforms.
Deep-aquifer iron content produces orange-brown staining at sprinkler-overspray zones and on glass below copper or galvanized exterior fixtures. Oxalic acid required — converges with the protocol Elly Giordano documents for Piedmont iron-clay staining in North Carolina.
At a published 130 mg/L the supply is just over the line into hard water, and the utility is unusually frank about it — its own framing is that Green Bay has neither soft nor hard water but sits in the middle. For glass that means deposits on evaporation and nothing worse.
Residential window cleaning in Green Bay typically runs $8–13 per pane or $240–430 for a standard single-story exterior. Pane count drives the top of the range on the newer east-side and Bay Settlement stock, where glazing areas are large.
Green Bay's drier, frost-free months are July to September, by NOAA's 1991–2020 normals for the Green Bay station, where June brings the most rain. The calendar on this page marks July (after the May 21 bloom and after smoke season). Frost nights usually run from October 9 to April 30.
Yes, if the rinse is squeegeed off before it dries: Green Bay Water Utility publishes dissolved solids of 150 mg/L, between this site's two dissolved-solids flags. Water left to dry leaves mineral scale; fresh spots lift with a mild acid. Treatment starts with coagulation, pre-chlorination, rapid mix and flocculation.
In Green Bay the dominant residue patterns include carbonate deposit from a 130 mg/l lake michigan supply — enough to mark glass on evaporation, not enough to etch and fine paper-mill particulate along the fox river corridor, heaviest on downwind elevations. Mineral marking is a constant, because the supply does not move seasonally.
Single-storey post-war stock on the east and west sides is reasonable homeowner work, provided the panes are finished to a dry edge rather than left to evaporate. The Astor Historic District is not beginner work at any storey — old putty and original glass punish a scraper — and the Broadway District shopfronts are a frequency contract rather than a one-off job.
The nineteenth-century core south-east of downtown, and the part of Green Bay where the glass is genuinely old. Assume original or early-replacement sash until someone proves otherwise, keep steel off it, and treat putty lines as the fragile part of the job rather than the frames.
Just over the Wisconsin line