Over two consecutive days in April, the Environmental Protection Agency (EPA) announced plans and actions designed to ensure drinking water safety for residents of New York and California communities where the drinking water is or has been contaminated.

Cassel/Hicksville Groundwater Contamination Superfund

On April 3, 2024, the EPA issued a final cleanup plan to address groundwater contaminated with volatile organic compounds (VOCs) at a portion of the New Cassel/Hicksville Groundwater Contamination Superfund site in N.Y. at the Towns of Hempstead, North Hempstead, and Oyster Bay in Nassau County.

The Cassel/Hicksville final cleanup plan is designed to prevent potential exposure to the VOC-contaminated groundwater, help minimize the potential for the contaminated groundwater to spread further, and treat the groundwater to meet strict federal and state drinking water standards, the EPA says. Under the plan, a network of wells and underground pipes would be installed in a residential neighborhood of Salisbury, N.Y., to collect and move contaminated groundwater to a new water treatment facility.

Residents in the impacted areas currently receive drinking water from public water supplies that have treatment systems installed, and water quality is monitored to ensure the drinking water meets federal and state standards, the EPA says. Many VOCs are known to cause cancer, while the health effects of some VOCs are not known because the extent and nature of potential health effects of VOCs depend on many factors, including the level and length of exposure, according to the EPA.

According to the EPA, the next phase of work involves developing detailed specifications for the various components of the treatment system. As part of this phase of work, referred to as the remedial design, additional groundwater monitoring wells will be drilled and sampled. Based on the results of the remedial design phase, the EPA will determine where the extraction wells and water treatment facility will be built.

Options for how the treated water will be released will also be evaluated during the design of the cleanup plan, including releasing treated water back to the ground, to surface water, to a recharge basin, or into the sewer, according to the EPA. The final cleanup plan also requires long-term groundwater quality monitoring and relies on existing county and state restrictions on groundwater use to ensure that public drinking water wells are not installed without a permit, the agency says.

Torres Martinez Desert Cahuilla Indians Reservation

On April 4, 2023, the EPA said that previously identified arsenic in groundwater that surpassed the federal limit and was found in 20 mobile home parks located in the California community of Torres Martinez Desert Cahuilla Indians Reservation in the Eastern Coachella Valley has been reduced to safe levels, and therefore, safe drinking water has been restored to over 900 residents living in those mobile home parks.

In 2020, the EPA began investigating numerous mobile home parks located within the Torres Martinez Desert Cahuilla Indians Reservation for compliance with the arsenic limits under the Safe Drinking Water Act, the agency says. That investigation was part of an increased focus on the area, including enforcement efforts related to drinking water at the Oasis Mobile Home Park, the DD Mobile Home Park, and the Indian Village Mobile Home Park, according to the EPA.

As a result of the information gathered, the EPA identified another 20 mobile home parks within the reservation where drinking water comes from groundwater and, therefore, may contain arsenic levels above the federal limit. Of the 20 mobile home parks, only 13 parks’ drinking water systems were previously regulated by Riverside County, Calif. Seven of the 20 mobile home parks’ drinking water systems, serving 287 people, had never been subject to regulatory oversight, had no regulated arsenic treatment systems in place, and had no information about the current condition of the drinking water being served, EPA said.      

The EPA’s investigation resulted in the agency developing a comprehensive approach to addressing the needs of the communities living in those 20 mobile home parks, including federally funded sampling efforts, enforcement actions, compliance assistance, and the EPA forming a partnership with a local non-profit organization, Pueblo Unido Community Development Corp. (PUCDC).

From December 2021 through September 2022, the agency says that the EPA issued Safe Drinking Water Act emergency administrative orders (EAO) to nine mobile home parks where the arsenic levels in the drinking water exceeded the federal limit of 10 parts per billion. Each EAO must provide safe alternative water, install regulated arsenic treatment systems, and comply with all other Safe Drinking Water Act standards and regulations.

While pursuing those enforcement actions, the EPA, in coordination with PUCDC, provided compliance assistance to the other mobile home parks, including installing point-of-use arsenic treatment devices in over 220 homes to ensure their drinking water would comply with federal arsenic limits, the agency says. 

In addition, the EPA has released the mobile home parks Arellano, Castro Ranch, Desert Rose, Gamez, Gonzalez, and Sandoval from their EAOs because they have returned to compliance with the arsenic limit and other EAO requirements. The EPA continues to monitor the progress of mobile home parks that are still under EAOs.