Walnut Grove MHP

Monitoring Violation: 2 violations, Jul 2024 to Feb 2025. The system did not complete required monitoring. This does not show that a contaminant was found.

What the rule requires: The 2013 RTCR (effective 2016) replaced the original TCR. It triggers automatic E. coli testing whenever total coliform is found. A single E. coli-positive sample is an acute MCL violation. It also requires systems exceeding 5% total coliform-positive samples to conduct a formal assessment and correct any deficiencies, helping prevent contamination before it escalates.

Treatment Technique Violation, health-based: 1 violation, Jul 2024 to Oct 2024. The system did not carry out a required treatment process or corrective action.

Monitoring and Reporting: 1 violation, Mar 2024 to Mar 2024. The system did not complete required monitoring, or did not report the results on time. This does not show that a contaminant was found.

Contaminants on the record: Groundwater Rule (GWR), E. coli (Escherichia coli).

Groundwater Rule (GWR), health effects: Protects against enteric viruses, which can contaminate groundwater via cracked well casings, failing septic systems, or animal waste. Viruses persist longer in groundwater than in surface water. Hepatitis A and norovirus are the primary pathogens of concern. Limit: Treatment technique: 4-log virus treatment required when source water has fecal indicators or significant sanitary deficiencies

E. coli (Escherichia coli), health effects: Most E. coli strains cause diarrheal illness. Some strains (e.g., O157:H7) produce toxins causing severe bloody diarrhea, hemolytic uremic syndrome (HUS — a form of kidney failure), and death — especially in children under 5 and the elderly. Even non-pathogenic strains in drinking water indicate that disease-causing organisms may also be present. Limit: Zero (one confirmed positive sample = acute MCL violation)

Treatment Technique Violation, health-based: 1 violation, Dec 2024 to Oct 2025. The system did not carry out a required treatment process or corrective action.

Monitoring and Reporting: 4 violations, Dec 2024 to Oct 2025. The system did not complete required monitoring, or did not report the results on time. This does not show that a contaminant was found.

What the rule requires: The 1991 LCR uses action levels rather than MCLs: if the 90th percentile of high-risk tap samples exceeds 15 ppb lead or 1.3 mg/L copper, the system must take escalating corrective actions. Violations typically indicate failure to maintain adequate corrosion control — the treatment that keeps lead from leaching out of pipes, solder, and fixtures.

Health effects: Lead: no safe level for children. Causes irreversible neurological damage, impaired cognitive development, behavioral problems, and reduced IQ in children under 6. In adults: hypertension, cardiovascular disease, kidney damage. Copper: acute gastrointestinal distress at high levels; liver/kidney damage at very high chronic levels. Limit: Action levels: lead 15 ppb, copper 1.3 mg/L — 90th percentile of tap samples at high-risk sites

Other Violation: 2 violations, Sep 2024 to Mar 2026. A requirement other than monitoring, reporting, or a contaminant limit, such as public notice or the annual water quality report.

Contaminant on the record: Public Notification Rule.

Other Violation: 1 violation, Jul 2024 to Jul 2024. A requirement other than monitoring, reporting, or a contaminant limit, such as public notice or the annual water quality report.

What the rule requires: Community water systems must deliver an annual water quality report (Consumer Confidence Report) to all customers by July 1, covering the previous year. It must list all detected contaminants, compare them to MCLs, identify source water, and include educational language about lead. A violation means the report was not delivered on time or was incomplete.