Tapcensus

Darlington Estates

Community water system in Rapid City, Pennington County, South Dakota, serving 25 people from ground water. 2 rules violated in the past three years. Privately owned.

People served 25 ground water
Rules violated, past 3 years 2 one rule can carry several violations
Unresolved 0 rules currently in violation, EPA data updated Oct 7, 2026
Quarters with violations 4 of the last 12 quarters

Quarterly compliance history

–Q3
2023
–Q4
2023
–Q1
2024
–Q2
2024
–Q3
2024
–Q4
2024
–Q1
2025
–Q2
2025
VQ3
2025
SQ4
2025
SQ1
2026
SQ2
2026
–Q3
2026
–No violation identified VViolation identified SSerious violator (EPA enforcement priority) UUndetermined Oldest quarter on the left. Quarters 1 to 12 are the twelve most recent official quarters at EPA's last data refresh; the 13th is the quarter in progress at that refresh, which EPA reports as undetermined.

Rules violated in the past three years

Jul to Sep 2023 to Jul to Sep 2026

Stage 1 Disinfectants and Disinfection Byproducts Rule

Treatment Technique Violation Health-based

1 violation, Nov 2025 to May 2026 · Stage 1 Disinfectants and DBP Rule
EPA rule code 210 · 1 violation recorded, 1 health-based

Treatment Technique Violation, health-based: 1 violation, Nov 2025 to May 2026. The system did not carry out a required treatment process or corrective action.

Contaminant on the record: Stage 1 Disinfectants and DBP Rule.

Stage 1 Disinfectants and DBP Rule, health effects: See TTHMs (2950) and HAA5 (2456) for their specific health effects. Bromate is a probable human carcinogen (Group B2). Chlorite at elevated levels can cause hemolytic anemia, particularly in infants, developing fetuses, and individuals with certain enzyme deficiencies. Violations indicate the system exceeded one or more of these byproduct or disinfectant limits. Limit: TTHM: 0.080 mg/L; HAA5: 0.060 mg/L; Bromate: 0.010 mg/L; Chlorite: 1.0 mg/L

Radionuclides and Revised Rad Rule

Maximum Contaminant Level Violation Health-based

4 violations, Jul 2025 to Mar 2026 · 2 contaminants · 4 measured values
EPA rule code 340 · 4 violations recorded, 4 health-based

Maximum Contaminant Level Violation, health-based: 4 violations, Jul 2025 to Mar 2026. A sample exceeded the maximum contaminant level EPA allows in drinking water.

Measured
Combined Radium (-226 and -228) 13 PCI/L

Jan to Mar 2026

Gross Alpha, Excl. Radon and U 25 PCI/L

Jan to Mar 2026

Combined Radium (-226 and -228) 10 PCI/L

Oct to Dec 2025

Combined Radium (-226 and -228) 7 PCI/L

Jul to Sep 2025

Contaminants on the record: Gross Alpha, Excl. Radon and U, Combined Radium (-226 and -228).

Gross Alpha, Excl. Radon and U, health effects: Alpha-emitting radionuclides accumulate in bone and soft tissue, delivering sustained internal radiation doses that increase lifetime cancer risk. There is no established safe threshold for ionizing radiation. Individual contributors such as radium-226 and polonium-210 have their own MCLs; gross alpha serves as a cost-effective screening tool that triggers more specific radionuclide analysis when exceeded. Limit: 15 pCi/L (excluding radon and uranium)

Combined Radium (-226 and -228), health effects: Radium is a bone-seeking radionuclide that accumulates in skeletal tissue after ingestion. Long-term exposure increases the risk of bone cancer and leukemia. There is no safe threshold for ionizing radiation — the MCL is set at a level balancing risk reduction with treatment feasibility. Children are particularly vulnerable due to higher rates of bone growth and calcium uptake. Limit: 5 pCi/L (combined Ra-226 and Ra-228)

About this data

Rules violated and the list above come from EPA's SDWIS violation records, one row per violation and contaminant, grouped by the rule each row belongs to. A violation counts when its non-compliance period ended on or after Jul 1, 2023, the start of the thirteen quarters ECHO's three-year figures cover, or is still open; it is unresolved when it was still open at EPA's data refresh on Oct 7, 2026. EPA's rule code 500, "Not Regulated", is left out, as in ECHO's counts. Each rule's violation count is EPA's, and one rule can carry several: a missed monitoring round for a group of contaminants is one violation per contaminant and period. Category names are EPA's violation categories.

ECHO's own summary count of rules violated agrees with this grouping for 98.8% of active systems nationally, and its count of rules being violated for 98.7%; where they differ, the figures here follow the rows listed.

A measured value shown with a rule is the sample result EPA recorded with that violation (SDWIS viol_measure), against the limit EPA recorded on the same row (state_mcl), both in EPA's unit as written; violations without a recorded value, such as missed monitoring, show none. Other measured contaminant levels are not part of this record; each system publishes them in its annual Consumer Confidence Report.

The system's location is the centre of the first town EPA lists the system as serving, from Census Bureau place files.

Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The South Dakota records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet.