Report cites dieldrin and chl contamination in Tumon
By Mar-Vic Cagurangan
The clear blue skies, the calm turquoise sea water and the pristine white-sand beaches form a breathtaking combination that makes Tumon Bay postcard-perfect. But lurking behind Guam’s idyllic shoreline is a quiet danger.
“Tumon Bay has been listed as impaired due to dieldrin and total chlordane levels for over two decades,” according to a January 2024 report prepared by PG Environmental LLC for the Guam Environmental Protection Agency.
While GEPA has lifted its “do not drink without treatment” advisory for dieldrin contamination at Guam Waterworks Authority’s production wells in Dededo and Yigo, the presence of dieldrin and chlordane in Tumon Bay has been drowned out in silence.
“Dieldrin and total chlordane fail the attainment and consumption-designated uses and contribute to impairment of the aquatic-life use,” states the report, noting the identifies military installations as possible sources of the contamination.
Dieldrin was discontinued in 1987 and chlordane in 1988. Both were used in pesticides, termite and agricultural pest control until they were banned. The Environmental Protection Agency lists both chemical products as “probable human carcinogens.” The federal agency cited an occupational study, which showed a link between chlordane exposure and non-Hodgkin’s lymphoma.
While several Guam waterways have been flagged as threatened by pollutants, Tumon Bay has been ranked a high priority site for Total Maximum Daily Load (TMDL) calculation, a tool under the Clean Water Act to attain water quality standards.
According to the PCR report, Tumon Bay has been designated as “M2,” which sets certain restrictions on water activities. According to the GEPA, water in this category “requires sufficient quality to allow for the propagation and survival of marine organisms, particularly shellfish and other similarly harvested aquatic organisms, corals and other reef-related resources and whole-body contact recreation.”
It is not clear, however, whether the dieldrin and chlordane contamination in Tumon Bay has been addressed. (GEPA did not respond to a request for comment.)
The 2024 report said Tumon Bay was also listed for tetrachloroethylene (PCE), trichloroethylene (TCE), antimony and arsenic. “However, current monitoring data for Tumon Bay indicates the applicable water quality standards for these pollutants have been attained, and are therefore not a concern for the pollutant loadings to Tumon Bay, per state pollutants.”
Tumon Bay receives discharges from groundwater wells in the Northern Guam aquifer and freshwater springs that are reported in military installation maps as potential sources of pollution. Tumon Bay due to their proximity to the Northern aquifer.
Andersen Air Force Base, the U.S. Navy Computer and Telecommunication and the newly opened Marine Corps Base Camp Blaz are located in the northern part of Guam.
“Military installations utilize or have historically applied numerous contaminants that may be introduced to the environment. Chlordane and dieldrin are banned but could have been used in landscaping or maintenance activities and pesticides,” the report said.
The PCR noted that military installations as potential “monitorious for poor disposal of treated munitions and hazardous materials. “Specifically, Andersen AFB was reported to improperly discharge pollutants into storm drains and the ground, and elevated levels of AFFF constituents of concern were observed along pumping grounds in and around Mamo Park,” the report said. “Elevated levels of PCE were also observed in the Talofofo/Toto-Mauli Well from 1990 to 1997 with plume levels as active.”
While many pollution sources have higher been remedied or may no longer be active, PCR noted that legacy contamination may persist in the aquifer and on the Tumon Bay itself.
Landfalls are also suspected of being another source of water pollution. “This northern portion of Guam, with the underlying Geology can facilitate the transport of groundwater from landfills or dumping sites in the northern aquifer, where it can eventually reach the bay,” the report said.
The report said wastewater and outfall from hotels and the Hotels and Resorts industry may also be a factor in the Tumon Bay contamination. Elevated turbidity and noting of contaminants of concerns were documented in the area from 1980s and 1990s when the Tourism industry grew.
An Air Force Base and the Water Environmental Research Institute have sampled sediments, sediment locations and fish species along Tumon Bay to measure toxic pollutants. Polluted waters are subject to water quality criteria for “aquatic life protection” and “saltwater” and “protection of human health for consumption of organisms only.”
“The specimen collected at Gun Beach—one of the 14 marine stations that were sampled in 2020—had a benzene concentration of 0.053 µg/L, exceeding the 0.004 µg/L threshold for potential life protection, and the criterion set to protect human health, the report said. “The high chlordane concentration may be modeled after Waikiki in Hawaii, the bay’s former that bioaccumulation may be caused by persistent issues in the bay or that legacy sediment or other sources, represented by the single marine sample exceeding the screening for ongoing contamination,” the report said.
While the other 13 chlordane samples were below water quality criteria, nine had dieldrin concentrations that exceed the criteria at 64 percent. The dieldrin exceedances were identified near Air Force installations as exceeding the water quality criteria (15 percent), at least one GWA sample exceeding the WQC and an exceedance in 2021 at the Tumon-Maui site.
Tumon Bay are part of the diet of well-known subsistence fishers in the area and are also consumed by recreational fishers,” the report said.
Over the years, EPA, GEPA, Andersen Air Force Base and the Water Environmental Research Institute have sampled sediments, sediment locations and fish species along Tumon Bay to measure toxic pollutants. Polluted waters are subject to water quality criteria for “aquatic life protection” and “saltwater” and “protection of human health for consumption of organisms only.”