Emergency declared over water contamination in Guam's northern village

By Pacific Island Times News Staff

Acting Gov. Josh Tenorio today declared a state of emergency to address the chemical contamination in water wells in Yigo.

“Like you, I am alarmed by the information we know, and even more alarmed by what we don’t know, including the source of this contamination,” Tenorio said in his video message.

On Sept. 12. the Guam Waterworks Authority issued a Tier 1 or "do not use" advisory for dieldrin, a federally unregulated, manmade chemical used as an insecticide and termiticide from the 1950s until 1987.

Krystal Paco San Agustin, communications director, said only one well in Yigo is contaminated. Another contaminated well in Dededo has been taken offline.

The Guam Environmental Protection Agency first detected dieldrin in Guam water wells in 2023.

According to the Guam EPA's risk assessment document released in November 2024, the USEPA has classified dieldrin as a probable human carcinogen.

"Long-term consumption of water that exceeds the dieldrin IAL of 0.2 micrograms per liter (ug/L or parts per billion – ppb) represents an unacceptable long-term likelihood, or risk of developing cancer. Similarly, long-term consumption of water with elevated levels of dieldrin has been associated with adverse impacts on the liver and nervous system," the document states.

GWA said the dieldrin monitoring data and analysis of the distribution system

configuration determined that of a total of 43,780 accounts, 1,112 ratepayers in the Santa Rosa area receive their water from one well, which has concentrations of dieldrin above the interim action level set by the Guam Environmental Protection Agency.

The average levels for dieldrin sampled at the Santa Rosa well were greater than 0.2 parts per billion, GWA told the residents.

“Although it was commonly used as a pesticide, the exact source of dieldrin contamination affecting this area is unknown,” GWA and GEPA said in a joint statement.

Officials speculate that areas in Guam, where dieldrin may have been 

used were disturbed as a result of the demolition of older structures for new construction and development. “This disruption exposes potentially contaminated soil to rainfall – causing dieldrin to percolate into our groundwater sources,” they said.

GWA said grants and bond funding will cover the granular activated carbon treatment systems, which were estimated to cost $6.4 million.

GWA said it has selected a contractor to perform the treatment system, which is expected to be completed by summer 2026.

According to the executive order, "GWA confirms that dieldrin levels in 97 of its 99 wells do exceed IAL levels."

In a FAQ sheet, GWA explained that while dieldrin has been detected, it has not received orders from either GEPA or USEPA to shut off water services to areas receiving water above GEPA’s IAL for dieldrin.

"GEPA has not issued any advisories against using your water for showering, washing dishes, laundry, irrigation or water activities," reads the FAQ. "Based on GEPA’s compliance requirements, water exceeding their IAL for dieldrin must not be consumed without treatment. Shutting off water may cause more severe and immediate public health risks by diminishing hygiene and sanitation."

Tenorio signed an executive order declaring a state of emergency and releasing $250,000 in funds to expedite the water decontamination treatment.

“With this, GWA has the resources to act quickly to get safe drinking water to affected families,’ Tenorio said.

The emergency funds will enable GWA to immediately procure filters and other supplies, like point-of-entry systems that can filter water before it even reaches the taps in our homes, he added.

"The GWA has the flexibility to use the funds as needed," Paco SanAgustin said. "Our expectation is that they will use the funds to supply drinking and cooking water to households."

He ordered monthly testing and public reporting of testing results from the affected wells, and regular updates on GWA’s efforts to treat and clean these contaminated water systems. 

“Recognizing the lengthy process to clean affected wells, we have also engaged with federal partners like USEPA and the local military commands to augment our efforts with federally-controlled supplies and equipment,” Tenorio said.

"The presence of all constituents in GWA water supplied to GWA customers, including dieldrin, has been provided to all the authority’s customers in the

annual Water Quality Report," GWA said.

"Starting in 2023, in response to GEPA’s work to evaluate the risk of this pesticide, specific information on dieldrin was included in the annual water quality reports received by GWA customers," it added.

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