Eugene's water is very soft at 16 to 18 mg/L, moss and green algae grow through the long wet season, and valley grass-seed pollen follows it.
Eugene's water is very soft, drawn from Cascade basalt country, so mineral spotting is a non-issue; moss and green algae through the long wet season, then valley grass-seed pollen, are what cover the glass. June to September is the dry window and July and August capacity is the tightest, while a single-story exterior runs $240 to $430.
EWEB's own 2025 testing puts hardness at 16 to 18 mg/L, averaging 17, at the soft end of the national range, and the geology explains it — Cascade basalt weathers to silicates rather than to the carbonates that make water hard. Practically, mineral spotting is not what fails a job in Eugene, and any product bought to fight scale here is solving a problem the city does not have. The consequence of soft, weakly buffered water is that cleaners act at close to their stated strength, so the discipline is dilution and rinsing rather than concentration.
| Hardness | 16–18 mg/L as CaCO₃ Averaging 17 in the utility's 2025 distribution-system testing, which is soft on the USGS ladder, as published by Eugene Water and Electric Board. |
|---|---|
| pH | 7.9 (range 7.8–8.1) |
| Alkalinity | 25 mg/L as CaCO₃ (range 23–26) |
| Iron | not detected |
| Manganese | not detected |
| Sodium | 7 mg/L (range 6.4–7.8) |
| Chloride | 3.7 mg/L (range 3.4–4.2) |
| Total dissolved solids | 55 mg/L (range 51–61) |
| Disinfectant | free chlorine |
| Source and treatment | McKenzie River surface water, per the EPA SDWIS federal record · Powdered activated carbon, pre pH adjustment, coagulation, flocculation, rapid mix, sedimentation and rapid sand filtration, post mixed-oxidant disinfection and caustic soda for pH · No softening step. |
Not in the report: corrosion index.
SOURCE · Eugene Water & Electric Board 2025 Water Testing Results, with the EPA SDWIS federal treatment record · How we source these numbers
The calendar is the opposite shape from a desert market: a long wet winter when exterior work is mostly impractical and organic growth advances unchecked, then a short dry summer that has to carry the year. Shaded elevations come out of winter with established moss and film rather than loose dirt, which makes the first dry-weather service the heaviest by a wide margin. Grass pollen peaks in late spring and is worth waiting out. Smoke episodes in late summer are an unscheduled extra rather than part of the cycle.
OREGON SEASON BY SEASON →Eugene drinks from one river and nothing else — a Cascade source rising at Clear Lake, drawn downstream at Springfield, with a watershed over 96 percent forested and largely federal land. Young volcanic rock yields soft, lightly mineralised water, so scale is not the problem here. Biology is: a wet season from October to May keeps moss and green film working on every shaded elevation, valley grass-seed pollen is among the heaviest in the country, and the productive exterior window is a short dry summer.
Eugene takes all its drinking water from a single river that rises in the Cascades at Clear Lake, and the utility draws it downstream at Springfield rather than in the city itself.
That watershed is exceptionally intact — more than 96 percent forested, roughly 70 percent federal land, and something near two fifths of the public portion lying inside a designated wilderness. The supply is clean because almost nobody lives above the intake.
One river supplies both Eugene and Springfield, around 200,000 people, which makes this a genuinely single-source city with no groundwater blend to shift the chemistry seasonally.
Young Cascade volcanic rock weathers to silicates rather than carbonates, and the result is water at the soft end of the national range with very little dissolved mineral in it.
The parameter that follows from that is low alkalinity — 23 to 26 mg/L in EWEB's 2025 testing — which is worth understanding: soft, poorly buffered water means a cleaner is not being tempered by the supply and behaves close to its label strength in either direction.
Scale is effectively a non-problem here. What replaces it is biology, and in the Willamette Valley that is relentless — a wet season running from October through May keeps moss, algae and green film alive on any surface that does not get direct sun.
North elevations, shaded frames and the bottoms of glazing channels stay damp for months at a stretch, so organic growth establishes there over winter and is waiting in spring rather than starting then.
The grass-seed industry that dominates the surrounding valley gives this area some of the heaviest grass pollen loads in the country through late spring, and it is a fine, sticky pollen that adheres rather than blowing off.
The dry summer is short and it is the whole productive season for exterior work. Between roughly July and September the valley barely rains, and a year's exterior schedule has to fit inside that window plus the shoulders either side.
Wood smoke and, in recent years, wildfire smoke settle into the valley because the surrounding hills trap air, and smoke film is oily rather than dusty — it smears under a dry cloth and needs a detergent.
Seasonality compresses the market hard, and the short dry window is the dominant commercial fact — capacity in July and August is the binding constraint and pricing should reflect that rather than treating the year as uniform. Condition at first service drives the residential quote, because a winter's growth is a different job from a maintenance visit. Campus and riverfront contract work prices on scheduling access, and the hill neighbourhoods price on canopy, slope and pane count.
Summer glass is easy homeowner work and the soft water genuinely helps — it rinses clean and leaves almost nothing behind. The thing that catches people is established moss and green film, which needs a mild detergent and dwell time rather than force; scrubbing it dry drags grit across the surface and achieves less. Anyone tempted to pressure-wash moss off framed glazing should not: it drives water past the seals and into the frame, which is a more expensive problem than the moss was.
OPEN COST ESTIMATOR →2025 annual mean at the Eugene - Highway 99 (E99) monitor, 530 Pacific Highway N, 2.1 km north-west of the city (EPA site 41-039-0059).
Largest air release: Murphy Plywood Co Eugene Operations, 2350 Prairie RD (wood products), 0.3 km outside the city limits, 45,105 lb in 2024.
Eugene's offenses chapter bars anyone from attaching to, detaching from or tampering with a water main, service pipe or connection without written consent from the Eugene Water & Electric Board's general manager, and it forbids letting water from air conditioners or other uses run from premises onto a sidewalk, street or alley, which covers hose runoff from a wash job.
Eugene Code 4.965: interfering with water mains or pipes · Eugene Code 4.975: water draining on street · checked September 2026
Eugene's environment chapter bars anyone from putting any substance other than stormwater into the city stormwater system unless it comes from firefighting or the city manager has approved it in writing, and it separately forbids letting wastewater flow from a property onto a public way or a neighbour's lot.
Eugene Code 6.446: discharge of foreign matter, preventative devices · checked September 2026
Altering a designated historic property in Eugene needs the planning director's approval, judged against rehabilitation criteria: keep the materials and features that give the building its character, repair deteriorated historic features rather than replace them, and avoid conjectural additions. Original sash and old glass therefore count as features to keep, not just fittings to swap out.
Eugene Code 9.8175: historic property alteration approval criteria · checked September 2026
The defining west-side Oregon substrate problem. North-facing windows under heavy canopy build a green-black film of mixed photosynthetic organisms that needs different chemistry than a normal wash. Sodium percarbonate or a quaternary ammonium prerinse, dwell five to ten minutes, then squeegee. Bleach is the wrong tool — it strips, but it lifts paint and stresses gasket rubber.
PM2.5 and PM10 combustion particulate bonds to glass during smoke events. Behaves more like an oily film than a dust — surfactant matters more than mechanical action. Pre-wash dry-wipe is contraindicated, it streaks the residue across the pane.
EWEB's own 2025 testing puts hardness at 16 to 18 mg/L, averaging 17, at the soft end of the national range, and the geology explains it — Cascade basalt weathers to silicates rather than to the carbonates that make water hard. Practically, mineral spotting is not what fails a job in Eugene, and any product bought to fight scale here is solving a problem the city does not have.
Residential window cleaning in Eugene typically runs $8–13 per pane or $240–430 for a standard single-story exterior. Seasonality compresses the market hard, and the short dry window is the dominant commercial fact — capacity in July and August is the binding constraint and pricing should reflect that rather than treating the year as uniform.
Eugene's drier, frost-free months are June to September, by NOAA's 1991–2020 normals for the Eugene Mahlon Sweet Airport station, where December brings the most rain. The calendar on this page marks June (after the April 7 bloom and after smoke season and before frost). Frost nights usually run from October 23 to April 11.
Usually yes: Eugene Water and Electric Board publishes dissolved solids of 55 mg/L, low enough that tap-rinsed glass tends to dry clean. Iron, manganese, sodium and chloride all sit under this site's flags (highest: sodium up to 7 mg/L). It draws on McKenzie River surface water.
In Eugene the dominant residue patterns include moss, algae and green film through a long wet season and heavy grass-seed pollen from the surrounding valley. The calendar is the opposite shape from a desert market: a long wet winter when exterior work is mostly impractical and organic growth advances unchecked, then a short dry summer that has to carry the year.
Summer glass is easy homeowner work and the soft water genuinely helps — it rinses clean and leaves almost nothing behind. The thing that catches people is established moss and green film, which needs a mild detergent and dwell time rather than force; scrubbing it dry drags grit across the surface and achieves less.
The commercial core, mid-century civic stock reworked around a pedestrian spine. Large modern frontages, straightforward access and the most schedulable commercial work in the city. Whiteaker and South Eugene and College Hill have their own housing stock and glazing as well.
Just over the Oregon line