Living in Green Valley, MD: what to set up and who to call
Green Valley has no town government of its own, so Frederick County runs its elections and most services, and its children attend Frederick County Public Schools. Xfinity is the only wired internet provider that reaches most of Green Valley.
I’m new in town
What to set up in Green Valley, and who provides it. Tap an answer for the details and where they come from.
Power, water and internet
Who to call to start service at a new address in Green Valley.
Power comes from Potomac Edison
Potomac Edison (The Potomac Edison Co.), an investor-owned utility, serves all of Green Valley. Its homes paid an average of 15.4¢ per kWh in 2025, about $172 a month (its average across Maryland, for customers on its standard service). Maryland lets you buy power from another supplier; 2% of Potomac Edison’s home customers do, and Potomac Edison still delivers it.
Service territory: HIFLD Electric Retail Service Territories (map dated Aug 2023). Prices and customers: EIA-861, 2025.
Water comes from Sam Hill Estates water system
The Sam Hill Estates water system supplies Green Valley: about 16% of residents live in its service area. Knolls of Windsor serves another 13%. Bradford Estates serves another 6%. About 65% of homes are outside any mapped community water system, most likely on private wells, which EPA doesn’t regulate. It draws ground water and serves 1,036 people in all.
No health-based violations reported to EPA in the five years to October 2026, like 78% of the 7,966 systems serving 1,001–3,300 people.
The latest lead result on file, the 90th percentile of homes sampled in Jan 2018–Dec 2020, was 1.7 ppb, below the 15 ppb action level that applied. It’s from 2020: EPA has no newer result for this system.
The system’s full record: EPA ECHO report
EPA SDWIS via Envirofacts (violations pulled Oct 9, 2026) and ECHO (lead samples, 2026Q3); service area: EPA Community Water System Service Area Boundaries v3.0. Violations are counted by the start of their compliance period. MD0100040.
4 home internet providers serve Green Valley
99% of 4,471 addresses can get 100/20 Mbps; 4% can get fiber.
| Provider | Technology | Addresses | Fastest (Mbps) |
|---|---|---|---|
| Xfinity | Cable | 99% | 2,000/250 |
| Verizon | Fixed wireless, Fiber | 15% | 2,300/2,300 |
| T-Mobile | Fixed wireless | 55% | 100/20 |
| AT&T | Fixed wireless | 19% | 25/3 |
FCC National Broadband Map, as of December 2025. Availability as providers report it, not speeds people get.
We don’t have Green Valley’s trash rules yet
Pickup rules, the dump and recycling in Green Valley.
Where your child goes to school
Public school districts and the school path by grade.
Green Valley is in Frederick County Public Schools.
A−School gradeSee Schools →U.S. Department of Education, NCES Common Core of Data, 2024–25. Enrollment rules and registration are the district’s.
No town hall: the county runs things
Green Valley is unincorporated, so Frederick County is the local government.
Election office: FVAP local election office directory, updated Jul 2023; jurisdictions: EAC EAVS 2024. Registration rules and links: vote.gov, updated Mar 11, 2026.
Green Valley spans 4 ZIP codes
ZIP codes where Green Valley residents live, with the share of the town in each.
| ZIP | Post office name | Share of Green Valley | ZIP’s residents in Green Valley |
|---|---|---|---|
| 21770 | Monrovia, MD | 38% | 63% |
| 21771 | Mount Airy, MD | 35% | 14% |
| 21754 | Ijamsville, MD | 23% | 41% |
| 20871 | Clarksburg, MD | 5% | 2% |
Census 2020 ZIP Code Tabulation Areas, by census block; post office names: GeoNames (CC BY 4.0). ZIPs created since 2020 are missing.
Getting around, the ER and the library
One line each; the subject pages have the rest.
ER: CMS hospital data. Library: IMLS Public Libraries Survey, FY2024.
Questions about living in Green Valley
Who supplies Green Valley’s drinking water, and has it had violations?
The Sam Hill Estates water system (EPA ID MD0100040). It reported no health-based violations to EPA in the five years to October 2026; 78% of systems its size had none. Its latest lead 90th percentile was 1.7 ppb (Jan 2018–Dec 2020), against a 15 ppb action level.
Who provides electricity in Green Valley?
Potomac Edison (The Potomac Edison Co.), an investor-owned utility. Its homes paid about 15.4¢ per kWh in 2025 (EIA).
What internet providers serve Green Valley?
Xfinity, Verizon, T-Mobile, AT&T (FCC, as of December 2025).
What ZIP codes are in Green Valley?
21770 (38%), 21771 (35%), 21754 (23%), 20871 (5%), by share of residents. Census 2020 ZIP Code Tabulation Areas.
What school district is Green Valley in?
Frederick County Public Schools.
How do I register to vote in Green Valley?
In Maryland you can register online until 21 days before Election Day, in person up to and including Election Day, or by mail (postmarked 21 days before). Elections here are run by the Frederick County Board of Elections. Check your registration at voterservices.elections.maryland.gov.
Sources & dates
Every answer above names its source. Here they are with their dates.
- Water: EPA SDWIS (Envirofacts, pulled Oct 9, 2026), ECHO SDWA 2026Q3, EPA CWS Service Area Boundaries v3.0.
- Power: HIFLD Electric Retail Service Territories (map Aug 2023); EIA-861 final 2025.
- Trash: OpenStreetMap, Geofabrik extract of Oct 9, 2026. © OpenStreetMap contributors (ODbL).
- ZIP codes: Census 2020 ZCTA relationship files; GeoNames postal codes (CC BY 4.0).
- Schools: NCES Common Core of Data, 2024–25.
- Registration: vote.gov, updated Mar 11, 2026 (read Oct 10, 2026). Official sites and area codes: Wikidata.
- Election office: FVAP local election office directory (fetched Oct 10, 2026; each record dated), EAC EAVS 2024 jurisdictions; registration and lookup links from vote.gov’s state data, checked Oct 10, 2026.
- Internet: FCC National Broadband Map, as of December 2025.