Cheyenne blends mountain snowmelt with High Plains aquifer water, and the Board's own page puts finished hardness at 59 mg/L on average, 46 to 69.
Cheyenne blends mountain snowmelt with High Plains aquifer water, and the Board of Public Utilities puts the finished result at 46 to 69 mg/L, averaging 59: soft to moderately hard, so a tap rinse rarely marks the glass. Wind is the real opponent in one of the windiest cities in the country, drying rinse water early and carrying grit. August and September give the calmest working weather, spring bookings carry the risk of lost afternoons, and a single-story exterior runs $220 to $370.
The Board's finished-water page gives hardness averaging 59 mg/L (46 to 69): soft to moderately hard water. Treat any grain figure quoted elsewhere for Cheyenne with suspicion: several disagree with each other and are pinned to reservoirs and aquifers the utility's own report does not name. What is genuinely known is the structure: mountain surface water blended with High Plains well water, in a ratio that moves with the year.
| Hardness | 46–69 mg/L as CaCO₃ Finished-water average 59 mg/L, range 46 to 69, on the BOPU's own water-quality pages; soft to moderately hard on the USGS ladder, as published by the Cheyenne Board of Public Utilities. |
|---|---|
| pH | 7.6 (range 7–7.9) |
| Alkalinity | 59 mg/L as CaCO₃ (range 48–76) |
| Sodium | 15 mg/L (range 10.3–24.7) |
| Chloride | 7.4 mg/L (range 5.7–9.2) |
| Disinfectant | free chlorine |
| Source and treatment | Surface water, per the EPA SDWIS federal record · Coagulation, flocculation, sedimentation and rapid sand filtration, post-chlorination, fluoridation and pH adjustment for corrosion control · No softening step. |
Not in the report: corrosion index, iron, manganese and total dissolved solids.
SOURCE · Cheyenne Board of Public Utilities, Finished Water Quality page, with the EPA SDWIS federal treatment record · How we source these numbers
The wind sets the calendar, not the mineral. Spring is the windiest stretch and the hardest season to finish a pane in; late summer into early autumn is the calm window, and it closes with the first hard frost, which at this elevation can arrive in the first week of September. Interstate frontage runs on its own interval because combustion film accumulates whatever the season is doing. The residential wash that holds is late August or early September, taken in a still morning.
WYOMING SEASON BY SEASON →Cheyenne is a two-source city at 6,060 feet in one of the windiest places in the country, and all three of those facts beat the water. The Board of Public Utilities publishes finished-water hardness averaging 59 mg/L, ranging from 46 to 69, on its water-quality pages. The method is set by the wind instead. Spring is the windiest season and a pane flashes dry in minutes, so work is chosen by forecast and by aspect rather than by route. The season is short at both ends because overnight freezes run from September into May, which makes the late-summer wash the one that has to be got right. The commercial book is interstate and railroad frontage, and that comes back on an interval rather than a season.
Cheyenne's water quality report does not name a hardness figure. Its annual report tables eighteen parameters; the Board's finished-water page adds hardness averaging 59 mg/L (46 to 69), sodium 15 and chloride 7.4.
The supply is a blend of two utterly different waters, which is the real reason a single number would be misleading here. Roughly 70 per cent is mountain surface water and about 30 per cent is groundwater from around 36 wells in four well fields west and northwest of the city, pumping the High Plains Ogallala and White River aquifers. Mountain snowmelt and High Plains groundwater do not carry the same mineral load, and the proportion shifts with the runoff year.
The surface half comes from two watersheds and a long way off. Douglas Creek is collected about 75 miles west in the Medicine Bow Mountains, stored in Rob Roy Reservoir and piped to Granite and Crystal Reservoirs; Crow Creek is collected about 30 miles west in the Laramie Mountains near Vedauwoo and stored in North Crow, Granite and Crystal. Crystal Reservoir and the South Crow diversion feed the R.L. Sherard treatment plant.
Cheyenne's most unusual arrangement is a trans-basin trade. Douglas Creek is a North Platte tributary, so every gallon the city takes there has to be replaced — and the replacement is collected in the Little Snake River watershed in the Sierra Madre about 110 miles west, piped under the Continental Divide into Hog Park Reservoir, released into the North Platte and recaptured in Seminoe. The water in a Cheyenne tap is legally entangled with two river basins.
The treated water is deliberately conditioned rather than left as it arrives. The Sherard plant adjusts pH and alkalinity specifically to cut corrosiveness, a programme the city started in the early 1990s, and lead at the 90th percentile reads 3.0 ppb against a 15 ppb action level with copper at 0.38 ppm against 1.3. Filtered turbidity holds at or under 0.09 NTU against an allowable 0.3.
Gross alpha activity reads 10.1 pCi/L against a 15 MCL — the highest-sitting radionuclide figure in the report, and a normal consequence of pumping High Plains aquifer water through uranium-bearing sediment. Uranium itself is 2.3 to 2.6 ppb against a 30 limit. None of it touches a window, but it is the signature of the groundwater half of the blend.
Disinfection by-products sit moderately high for a system this clean: trihalomethanes from 27.2 ppb and haloacetic acids from 15.3 ppb, which is the organic load of reservoir water rather than anything wrong. Chlorine runs 0.1 to 1.2 ppm across the distribution system, a wide spread on a network that reaches from the Sherard plant to the Round Top storage tank.
Cheyenne sits at about 6,060 feet on the High Plains, and the wind here is a working condition rather than weather. The city is one of the windiest in the United States and the gap between the Laramie Range and the plains funnels it; a pane flashes dry in minutes on an ordinary spring afternoon, and spring is the windiest season of the year.
Above 6,000 feet the freeze-thaw window is long at both ends. Overnight freezes are routine from September into May, which means the practical exterior washing season is genuinely short and the autumn wash has to be timed against a hard frost that can arrive in the first week of September.
Rail and interstate freight define the commercial load. Cheyenne is the junction of Interstate 25 and Interstate 80 and a Union Pacific division point, and the combustion and brake-dust film on frontage along those corridors comes back on an interval that has nothing to do with season.
Cheyenne quotes carry weather risk the way coastal quotes carry access risk: a crew that loses an afternoon to wind has to recover the day, and spring bookings price accordingly. Beyond that it is conventional — reach on the newer north-east gable elevations, pane count on the larger west-side stock, and route density on the interstate frontage, which supports the recurring commercial contracts that keep residential rates competitive.
Wind is the reason to hire this out, and it is a bigger reason here than in almost any other city on this site. A homeowner who picks a calm morning will do fine; one who starts at two in the afternoon in April will be re-wetting glass that has already flashed off, which sets a streak permanently rather than fixing it. The historic sash downtown and in Rainsford is the other job to hand over — original glass of that age does not survive a scraper, and there is a lot of it.
OPEN COST ESTIMATOR →2025 annual mean at the Cheyenne NCore monitor, NCore - North Cheyenne Soccer Complex, 6 km north of the city (EPA site 56-021-0100).
Largest air release: Cheyenne Renewable Diesel Co LLC, 2700 E. 5TH Street (chemicals), inside the city limits, 886 lb in 2024.
Cheyenne's code makes it unlawful to waste water from the public system, metered or not, and lets BOPU shut off service over unrepaired leaks. Filling a tank from a hydrant or any unmetered point needs a BOPU meter or construction hydrant permit, and system water may be used only on the customer's own premises unless BOPU allows otherwise.
Cheyenne Code 13.08.040: unlawful water-system activities, waste and hydrant use · checked September 2026
Only stormwater may enter Cheyenne's storm drain system or watercourses; any material that causes or adds to a breach of Wyoming's water quality standards is barred, and starting or continuing such a discharge is prohibited.
Cheyenne City Code §13.28.090: ultimate responsibility of discharger · checked September 2026
Before applying for a building permit for new construction, a significant alteration or improvements on a property in Cheyenne's designated historic protective area, the owner must obtain a certificate of appropriateness.
Cheyenne City Code §15.50.050: certificate of appropriateness required · checked September 2026
Late-winter and early-spring snow-melt residue at higher elevations carries chloride-residue, mineral residue, and organic residue composite. Percarbonate-citric ladder protocol on the worst-affected stock.
The Board's finished-water page gives hardness averaging 59 mg/L (46 to 69): soft to moderately hard water. Treat any grain figure quoted elsewhere for Cheyenne with suspicion: several disagree with each other and are pinned to reservoirs and aquifers the utility's own report does not name.
Residential window cleaning in Cheyenne typically runs $7–12 per pane or $220–370 for a standard single-story exterior. Cheyenne quotes carry weather risk the way coastal quotes carry access risk: a crew that loses an afternoon to wind has to recover the day, and spring bookings price accordingly.
Cheyenne's drier, frost-free months are August and September, by NOAA's 1991–2020 normals for the Cheyenne station, where May brings the most rain. The calendar on this page marks August (after the May 20 bloom and after smoke season). Frost nights usually run from October 1 to May 12.
Yes, if the rinse is squeegeed off before it dries: the Cheyenne Board of Public Utilities publishes hardness of 46–69 mg/L, between this site's two dissolved-solids flags. Iron, manganese, sodium and chloride all sit under this site's flags (highest: sodium up to 15 mg/L). Treatment starts with coagulation, flocculation, sedimentation and rapid sand filtration.
In Cheyenne the dominant residue patterns include soft to moderately hard water: finished-water hardness averages 59 mg/l on the board's own page and two mineral loads in one supply — mountain snowmelt blended with high plains aquifer groundwater in a proportion that shifts with the runoff year. The wind sets the calendar, not the mineral.
Wind is the reason to hire this out, and it is a bigger reason here than in almost any other city on this site. A homeowner who picks a calm morning will do fine; one who starts at two in the afternoon in April will be re-wetting glass that has already flashed off, which sets a streak permanently rather than fixing it.
The historic core and the residential district beside it carry Cheyenne's oldest glazing — late nineteenth and early twentieth century sash, much of it original, on streets that see the whole city's traffic film. Heritage handling and a short interval at the same time, which is an awkward combination to price.
Just over the Wyoming line