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WaterSafeCheck

ZIP Code 91990 Water Quality Report

Potrero, CA

Safety Score
C

Water Safety Grade

Fair — Some compliance concerns

Health Violations

16

Total Violations

20

Lead Risk

N/A

Contaminants

1

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Active Water Quality Issues Detected

EPA records show 20 unresolved violations. Contact Twin Lakes Resort for current status.

About Tap Water in ZIP Code 91990

Tap water in ZIP code 91990 (Potrero, CA) receives a C grade (score: 55/100) based on EPA monitoring data. While the water from Twin Lakes Resort is treated and regulated, this area has a moderate violation history that residents should be aware of.

Water System

Twin Lakes Resort

EPA ID: CA3701793

Water Source

Ground Water

Population Served

400 residents

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Lead Levels in ZIP 91990

EPA action level: 15 ppb | Public health goal: 0 ppb

Lead Data Not Available

Lead testing data was not found in EPA records for ZIP code 91990. This may occur with very small systems or systems that report under a parent utility. Contact Twin Lakes Resort directly to request lead testing results or a copy of their Consumer Confidence Report.
Lead Exposure Risk Rating
Unknown
Note: Lead levels above are the 90th percentile from EPA monitoring — meaning 90% of samples were at or below this level. Even "undetected" tap water lead doesn't account for lead leaching from home plumbing. If your home was built before 1986, individual tap testing is recommended.
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Violation History

Past 5 years — EPA SDWIS data

Twin Lakes Resort has recorded 16 health-based violations in the past 5 years — significantly above the national average. This volume of violations indicates serious and recurring compliance issues. Independent water testing and in-home filtration are strongly recommended. 20 violations are currently unresolved — meaning the issue has not yet been formally corrected in EPA records. This is a serious concern that residents should follow up on with their water utility.

Total Violations (5 yr)
20
Health-Based Violations
16
Unresolved Violations
20
Boil Water Advisories
0
Compliance Risk
Critical

Regulatory compliance risk is rated Critical — the highest risk category. Twin Lakes Resort has an extensive history of unresolved violations and enforcement actions. Independent water testing is highly recommended.

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Contaminants Detected

Contaminants with health-based violations on record

EPA records identify 1 contaminant associated with health-based violations in ZIP code 91990: Barium. These contaminants exceeded the Maximum Contaminant Levels (MCLs) established by the EPA under the Safe Drinking Water Act at some point in the 5-year monitoring period. The presence of these violations does not necessarily mean water is currently unsafe — water systems are often required to increase monitoring and treatment when violations occur. Review the annual Consumer Confidence Report for the most current status.

Barium

⚖ Enforcement Actions

3 enforcement actions have been issued against Twin Lakes Resort — a high number that reflects sustained compliance struggles. Enforcement actions escalate from administrative orders to financial penalties when utilities repeatedly fail to meet safe drinking water standards.
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Water Source & Environmental Factors

Ground Water

This system draws water from underground aquifers. Groundwater is naturally filtered through soil and rock, but can still contain naturally occurring minerals like arsenic, radium, or nitrates.

Water Source Type
Ground Water
EPA Radon Zone

Lower potential

Zone 3

EPA Radon Zone 3 — lower radon potential, though the EPA still recommends testing all homes.

🛡 What Should You Do? — ZIP 91990 Recommendations

  • ⚠ Use a certified NSF/ANSI 53 filter for drinking and cooking water if you have young children
  • ⚠ Never give unfiltered tap water to infants in formula — use certified bottled or filtered water
  • ⚠ Request a copy of the Consumer Confidence Report to see what was detected and when
  • ⚠ Call the EPA Safe Drinking Water Hotline: 1-800-426-4791

Frequently Asked Questions — ZIP 91990 Water Quality

Is tap water safe to drink in ZIP code 91990?+
Tap water in 91990 (Potrero, CA) is treated and regulated, but has a grade of C due to past violations. For most healthy adults, treated tap water is generally safe. Families with infants, young children, or immunocompromised individuals may want to use a certified water filter as a precaution.
What is the lead level in 91990 tap water?+
Lead level data from EPA monitoring is not available for 91990. Contact Twin Lakes Resort directly for the most recent lead testing results.
Who provides tap water to 91990?+
Tap water in ZIP code 91990 is provided by Twin Lakes Resort (EPA ID: CA3701793). This system serves approximately 400 residents. You can contact them directly for Consumer Confidence Reports, current advisories, and billing information.
What is the water source for 91990?+
ZIP code 91990 is served by ground water. Groundwater systems draw from underground aquifers. While naturally filtered, groundwater can still contain naturally occurring contaminants such as arsenic, radium, or nitrates at elevated levels in some regions.
Does 91990 have any active water quality violations?+
Yes — there are currently 20 unresolved violations on record for this water system. Unresolved violations indicate issues that have not yet been formally corrected in EPA tracking systems. Contact Twin Lakes Resort for the latest update.
How do I get a copy of my water quality report for 91990?+
Your water utility — Twin Lakes Resort — is required by law to send you an annual Consumer Confidence Report (CCR) by July 1 each year. You can also request it directly from the utility or find it online by searching "Twin Lakes Resort Consumer Confidence Report." The EPA's ECHO database also has historical compliance data.
What water filter should I use in 91990?+
The right filter depends on what contaminants are present. For lead, look for a filter certified to NSF/ANSI Standard 53. For chlorine byproducts (like THMs), NSF/ANSI 42 filters work well. For a broad range of contaminants including PFAS, look for NSF/ANSI 58 (reverse osmosis) systems. For ZIP code 91990, with detected contaminants including Barium, a multi-stage filter or reverse osmosis system is recommended.
Is 91990 tap water safe for babies and infants?+
Infants are especially vulnerable to lead, nitrates, and microbial contaminants in drinking water. Current EPA data for 91990 shows no available lead data — we recommend using a certified NSF/ANSI 53 lead filter as a precaution for infant formula. Always consult your pediatrician for guidance specific to your child's health.

Data Sources & Methodology

Water quality data for ZIP code 91990 is compiled from the EPA Safe Drinking Water Information System (SDWIS), EPA ECHO enforcement database, UCMR5 unregulated contaminant monitoring, and Consumer Confidence Reports filed by Twin Lakes Resort. Safety scores are composite metrics derived from violation history, lead levels, enforcement actions, and infrastructure risk indicators. Data reflects a 5-year monitoring window. Last dataset update: 2024. View EPA source data →