Public water system · MD0040035
ActiveWalnut Creek
At a glance
Walnut Creek (PWSID MD0040035) is an active community water system in Calvert County, Maryland. It reports serving 158 people through 56 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 3 violations for this system; none is health-based, and the most recent began in October 2014.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
158
Service connections
56
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Walnut Creek compare with other water systems in Calvert County?
By EPA's size categories, Walnut Creek is a very small system (500 people or fewer). Calvert County has 203 active public water systems. Its population served is about 59% below the county average of 384 people per system, and accounts for 0.2% of the 77,996 people reported by systems filed under the county. Across Maryland, the 2,992 active systems average 1,947 people each. Nationally, the average active community water system reports serving 6,703 people, so Walnut Creek is well below that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. Maryland has 422 active community water systems, 14% of the state's 2,992 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 2,870 Maryland systems (96%) list groundwater as their primary source.
Who owns and regulates Walnut Creek?
EPA lists Walnut Creek as owned by a local government. The MD state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 39 of the 203 active systems in Calvert County (19%) are also owned by a local government.
Does Walnut Creek have drinking water violations?
EPA's records list 3 violations for this system; none is health-based, and the most recent began in October 2014. The violations listed here began between July 2008 and October 2014. By type: 2 monitoring and reporting and 1 public notice, recordkeeping or other. The contaminant or rule involved most often is Lead and Copper Rule (2 of them). EPA lists 3 as resolved. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2014-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2011-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2008-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
All 3 violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
Walnut Creek: frequently asked questions
Who runs Walnut Creek?
Walnut Creek (PWSID MD0040035) is a community water system owned by a local government. It is regulated by the MD state drinking water program.
How many people does Walnut Creek serve?
Walnut Creek reports serving 158 people through 56 service connections in Calvert County, Maryland.
Where does Walnut Creek get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Walnut Creek have any drinking water violations?
EPA's records list 3 violations for this system; none is health-based, and the most recent began in October 2014. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is Walnut Creek's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. EPA's records list 3 violations for this system; none is health-based, and the most recent began in October 2014. For current results, consult the system's annual water quality report, EPA ECHO, or the MD state drinking water program.
Where can I find Walnut Creek's water quality report?
As a community water system, Walnut Creek must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Calvert County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Chesapeake Ranch Estates | Calvert | 9,500 | Community | Groundwater |
| Town of Chesapeake Beach | Calvert | 5,000 | Community | Groundwater |
| Prince Frederick | Calvert | 4,371 | Community | Groundwater |
| Solomons | Calvert | 3,811 | Community | Groundwater |
| Town of North Beach | Calvert | 3,000 | Community | Groundwater |
| Northern Middle & High Schools | Calvert | 2,470 | Non-transient non-community | Groundwater |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Walnut Creek, PWSID MD0040035, Maryland”, https://aquacensus.com/water-systems/maryland/walnut-creek-md0040035 (data as of October 1, 2026).