Dorado Ground Water Contamination

Overview

The Dorado Ground Water Contamination site sits in Dorado, Puerto Rico, and was added to the EPA's National Priorities List (NPL) in September 2016. The NPL is the roster of the nation's most serious hazardous waste sites. Groundwater at the site contains volatile organic compounds (VOCs), specifically trichloroethylene (TCE) and tetrachloroethene (PCE). These contaminants were first detected by the U.S. Geological Survey and Puerto Rico authorities in the 1980s and again between 1996 and 2000. EPA has determined both chemicals pose unacceptable risks to human health and the environment across the entire site.

The Puerto Rico Aqueduct and Sewer Authority (PRASA) shut down all contaminated wells. Two active water supply systems, Maguayo and Dorado Urbano, draw from uncontaminated sources that meet drinking water standards. A Super Aqueduct supplements the supply while groundwater use restrictions remain in place. EPA worked with the Department of Environment and Natural Resources (DNER) and completed a remedial investigation and feasibility study before finalizing a cleanup plan in September 2021.

EPA's chosen remedy uses monitored natural attenuation (MNA). MNA lets natural processes break down contaminants over time while regular monitoring confirms progress. The U.S. Army Corps of Engineers designed new monitoring wells in August 2022. Once installed, those wells will be checked every six months for the first two years, then annually. Cleanup is expected to take up to 18 years and cost roughly $830,000. Funding from the Bipartisan Infrastructure Law (BIL) supports the monitoring well installation. The entire site is managed as a single operable unit, and institutional controls also restrict land and groundwater use to protect public health.

EPA has confirmed that human exposure is under control and that contaminated groundwater migration is stabilized, with no unacceptable discharge to surface water. Cleanup construction began in September 2023 and is estimated to finish between September and November 2027. A long-term response action phase will follow. The site has not yet been deleted from the NPL, and a five-year review has not yet been completed.

Community members with questions can contact the EPA's Community Involvement Coordinator or the Remedial Project Manager. Site documents, including the 2021 Record of Decision, are available through EPA's Superfund database and in person at the Dorado Municipal Library at 331 Calle Mendez Vigo in Dorado, Puerto Rico.