Oasis Mobile Home Park Emergency Drinking Water Order, Thermal, CA
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Background
On September 14, 2021, EPA issued an Emergency Administrative Order under Section 1431 of the Safe Drinking Water Act An Act passed by the US Congress in 1974. The Act establishes a cooperative program among local, state and federal agencies to insure safe drinking water for consumers. (SDWA) 42 U.S.C. § 300i to Oasis Mobile Home Park, Thermal, California. EPA determined that conditions exist at Oasis’ public water system that may present an imminent and substantial endangerment to the persons served by the public water system. EPA’s decision was based on sampling results that indicated high arsenic levels, that exceeded the maximum contaminant level (MCL) [1], in the distribution system (premise plumbing), well source water, and at the entry point to the distribution system.
The Order and its requirements are necessary to ensure adequate protection of public health at the public water system. The Order requires, in part, that Oasis provide alternative water, notify the public of the high levels of arsenic, identify and correct the cause of the high arsenic levels, and perform increased monitoring and reporting.
Sampling Results
As part of EPA’s ongoing enforcement, EPA took arsenic [1] and iron [2] samples (iron levels were taken to better understand arsenic levels) at the kitchen taps of homes located in Oasis. The results, recorded in parts per billion (ppb) are below.
See the Sampling Zone Map for locations of the zones at the site.
| Sampling Location | Arsenic Result (ppb) | Iron Result (ppb) | Sampling Date |
|---|---|---|---|
| Zone 1 / A1 | 5.7 | 220 | 5/29/2024 |
| Zone 1 / A4 | 7.2 | ND | 5/29/2024 |
| Zone 1 / A5 | 6.3 | ND | 5/30/2024 |
| Zone 1 / A6 | 6.8 | 140 | 5/29/2024 |
| Zone 1 / A7 | 6.4 | ND | 5/29/2024 |
| Zone 1 / A8 | 4.8 | ND | 5/29/2024 |
| Zone 1 / A10 | 4.9 | 190 | 5/29/2024 |
| Zone 1 / A11 | 4.9 | 670 | 5/29/2024 |
| Zone 1 / A12 | 5.4 | 110 | 5/30/2024 |
| Zone 1 / A14 | 7.4 | 170 | 5/29/2024 |
| Zone 1 / A15 | 8.1 | 180 | 5/29/2024 |
| Zone 1 / A16 | 7.7 | ND | 5/29/2024 |
| Zone 1 / A17 | 6 | ND | 5/29/2024 |
| Zone 1 / A18 | 6.3 | ND | 5/29/2024 |
| Zone 2 / A1 | 5.3 | ND | 5/30/2024 |
| Zone 2 / A2 | 4.3 | 670 | 5/30/2024 |
| Zone 2 / A3 | 5.9 | 330 | 5/30/2024 |
| Zone 2 / A4 | 6.6 | ND | 5/30/2024 |
| Zone 2 / A5 | 5.8 | 250 | 5/29/2024 |
| Zone 2 / A8 | 4.9 | 190 | 5/30/2024 |
| Zone 2 / A10 | 6.6 | ND | 5/29/2024 |
| Zone 2 / A11 | 6.8 | 230 | 5/30/2024 |
| Zone 3 / A1 | 5 | 2,000 | 5/29/2024 |
| Zone 3 / A2 | 6.2 | ND | 5/30/2024 |
| Zone 3 / A3 | 6.6 | ND | 5/30/2024 |
| Zone 3 / A4 | 5.3 | 53 | 5/30/2024 |
| Zone 3 / A5 | 6.3 | ND | 5/29/2024 |
| Zone 3 / A6 | 7.6 | ND | 5/29/2024 |
| Zone 3 / A8 | 4.3 | 3,800 | 5/29/2024 |
| Zone 4 / A1 | 8.4 | ND | 5/29/2024 |
| Zone 4 / A2 | 4.1 | 200 | 5/30/2024 |
| Zone 4 / A4 | 3.3 | 7,000 | 5/30/2024 |
| Zone 4 / A5 | 7.3 | ND | 5/30/2024 |
| Zone 4 / A6 | 8.1 | ND | 5/30/2024 |
| Zone 4 / A7 | 6.5 | ND | 5/30/2024 |
| Zone 4 / A8 | 6.2 | ND | 5/30/2024 |
| Zone 4 / A9 | 5.8 | ND | 5/30/2024 |
| Zone 4 / A10 | 2.4 | 8,700 | 5/30/2024 |
| Zone 4 / A11 | 6.1 | ND | 5/30/2024 |
| Zone 5 / A2 | 6.9 | ND | 5/30/2024 |
| Zone 5 / A3 | 6.3 | ND | 5/30/2024 |
| Zone 5 / A4 | 6.3 | ND | 5/30/2024 |
| Zone 5 / A6 | 5.8 | ND | 5/30/2024 |
| Zone 5 / A7 | 7 | ND | 5/30/2024 |
| Sampling Location | Arsenic Result (ppb) | Iron Result (ppb) | Sampling Date |
|---|---|---|---|
| Zone 1 / A14 | 4 | 76 | 1/25/2024 |
| Zone 1 / A16 | 9 | 50 | 1/25/2024 |
| Zone 3 / A1 | 5 | 1,010 | 1/25/2024 |
| Zone 3 / A5 | 9 | 50 | 1/25/2024 |
| Zone 3 / A6 | 10 | 50 | 1/25/2024 |
| Zone 4 / A1 | 9 | 50 | 1/25/2024 |
| Zone 4 / A3 | 7 | 354 | 1/25/2024 |
| Zone 4 / A7 | 8 | 50 | 1/25/2024 |
| Sampling Location | Arsenic Result (ppb) | Iron Result (ppb) | Sampling Date |
|---|---|---|---|
| Zone 2 / A5 | 15.5 | 2,070 | 4/7/2023 |
| Zone 2 / A6 | 20.6 | 281 | 4/7/2023 |
| Zone 3 / A1 | 10.8 | 221 | 4/7/2023 |
| Zone 3 / A5 | 14.5 | 136 | 4/7/2023 |
| Zone 4 / A1 | 15.1 | 191 | 4/7/2023 |
| Zone 4 / A7 | 14.6 | 158 | 4/7/2023 |
| Zone 5 / A1 | 12.5 | 186 | 4/7/2023 |
Sampling Zone Map
Documents
- U.S. Department of Justice Complaint Against Oasis Mobile Home Park for Alleged Safe Drinking Water Act Violations (pdf)
- Emergency Administrative Order: Oasis Mobile Home Park (pdf)
- Oasis Mobile Home Park Drinking Water Fact Sheet (pdf)
- Oasis Mobile Home Park Water Filtration System Fact Sheet (pdf)
- Residential Flushing Procedure Handout (pdf)
- Arsenic and your Distribution System Brochure (pdf)
Footnotes
[1] EPA has established National Primary Drinking Water Regulations (NPDWRs) under the Safe Drinking Water Act (SDWA) that set mandatory water quality standards for drinking water contaminants. These are enforceable standards called "maximum contaminant levels" (MCLs) which are established to protect the public against consumption of drinking water contaminants that present a risk to human health. An MCL is the maximum allowable amount of a contaminant in drinking water which is delivered to the consumer. EPA set the MCL for arsenic at 10 parts per billion (ppb) to protect consumers against the effects of long-term, chronic exposure to arsenic in drinking water.
[2] EPA has established National Secondary Drinking Water Regulations (NSDWRs) that set non-mandatory water quality standards for 15 contaminants. EPA does not enforce these "secondary maximum contaminant levels" (SMCLs). They are established as guidelines to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color, and odor. These contaminants are not considered to present a risk to human health at the SMCL. The SMCL for iron is 300 ppb.