Hawaii flooding cleanup raises questions on pesticides and bacteria, as labs and soil tests continue
After late-February storms battered O‘ahu’s North Shore and left residents digging through flood-carried mud, the cleanup has sparked new questions about what hazards may linger in the affected soils and waterways. Officials have pointed to pesticide risk as a concern amid agricultural activity nearby, but state health testing has also found pathogens in mud and water—an issue that, according to experts, may pose the more immediate health threat while lab work continues.
The state Department of Health has detected several pathogens in mud and water on the North Shore since the storms, which led to contaminated water advisories for more than two weeks in areas hit by severe flooding from late February through March, according to the reporting. The department’s sediment testing found evidence of E. coli, salmonella and enterococcus, and it was still awaiting results for bacteria that cause staph and campylobacter.
The pesticide question hinges on additional results for “legacy pesticides,” a term used in the reporting for banned agricultural chemicals such as DDT or heptachlor. The Department of Health tested four sites for 22 different legacy pesticides and anticipated it would take two weeks to receive results.
In the meantime, experts and officials said the scale of rainfall would likely have reduced the concentration of any pesticide residues carried by floodwaters. The reporting cited the amount of rain from the Kona low storms—about 2 trillion gallons statewide—and quotes Qing Li, a professor at the University of Hawai‘i’s molecular bioscience and bioengineering department, saying it was unlikely that any pesticide residue would be found in problematic concentrations on the North Shore given the roughly 62 inches of rain there. Li also told reporters that while pesticide concerns exist, “The risk is not terribly high, based on my knowledge of the field,” and said the greatest risk was bacteria.
Concerns are not limited to potential illness from contaminated floodwater, as farmers worry about what the storm-carried mud and water may mean for their land and their future harvests. The reporting said flood-carried mud and water destroyed more than crops and machinery and could compromise the ability of some farms to maintain their organic certification. The University of Hawaiʻi College of Tropical Agriculture and Human Resilience is offering three months of free soil testing for flood-affected farmers so they can understand what has settled on their land, including nutrients, disease and pesticide residue, with the details still being finalized and announced soon by the college.
The organic-certification risk can also depend on how far pesticide exposure might have traveled and whether required safeguards were effectively present during extreme flooding. Parwinder Grewal, the agriculture dean at the University of Hawai‘i, said pesticides are “definitely a concern,” and Christian Zuckerman, vice president of the Hawaiʻi Farmers Union, said the flooding’s scale made it likely that some protective structures would not have worked as they do in normal rains. Zuckerman said some of the berms that help in ordinary storms probably did not function as intended during the extreme event, and he said organic farmers may have to wait three years after clearing their land to regain their status.
Farmers union officials also pointed to other kinds of contaminants that could have washed in alongside floodwaters. Zuckerman said asphalt and other contaminants from roadways could leach into soils, and he said future harvests—particularly leafy greens that take up significant nutrients from the soil—may face challenges if any pesticides or other contaminants washed onto fields from other farms. Hawai‘i’s pesticides branch manager Esther Riechert said the uptake varies by crop and by the types of toxins and pesticides in the soil, adding that floodwaters diluted those chemicals.
The regulatory landscape that governs how pesticides are used and tracked also drew attention as residents and advocates ask how the public can know what exposures might have occurred before and during the flooding. The reporting said agriculture, pest control and cleaning companies have registered more than 8,000 restricted-use pesticides with the Hawai‘i agriculture department, which regulates their use statewide. It added that the state does not hold information on where those pesticides are used or when, a point advocates have sought to change.
Several bills meant to increase restrictions or reporting requirements were killed this legislative session, the reporting said, while a single measure to digitize reports remained alive. It also described how one bill that would have banned a carcinogenic fumigant called 1, 3-dicholoropropene, known as Telone and used by Dole Food Company Hawaiʻi, died despite nearly 3-to-1 support in testimony. Anne Frederick, executive director for Hawaiʻi Alliance for Progressive Action and part of the Safe Farms Safe Food coalition, said the outcome showed “who has power and influence.”
The coalition’s research pointed to large amounts of carcinogenic fumigants and neurotoxic insecticides used in the Wahiawā-Waialua region from 2020 to 2022, according to the reporting. It cited that the coalition found more than 400,000 pounds used over that period and said about 300,000 pounds were used by Dole Food Company Hawaiʻi on its pineapple lands between Wahiawā and Waialua, with the coalition linking such chemicals to cancer, respiratory problems and neurological damage.
At the federal level, Frederick also warned that potential changes could further affect Hawaiʻi’s pesticide debate. The reporting said she raised concerns about steps to promote domestic glyphosate production and described glyphosate as a central issue in multibillion-dollar lawsuits and settlements involving cancer allegations. The story also said pesticides regulation and labeling, along with potential federal preemption of states in lawsuits tied to carcinogenic paraquat and glyphosate, were points of contention in the negotiations for the federal Farm Bill. U.S. Rep. Jill Tokuda, who serves on the House Agriculture Committee, told Civil Beat that the Farm Bill’s progress in recent months left it “lopsided in favor of Republican priorities,” and she said the pesticide provision was a “poison pill,” according to the reporting.
While scientists and regulators said the heavy rainfall likely diluted pesticide residues, the community and farmers’ organizations remain focused on continuing results—both for bacteria and for legacy pesticides—as well as on soil testing intended to support recovery. For residents, the lab timelines and farm-assessment programs define the next phase of deciding what risks persisted after the mud cleared and what steps farmers may need to take before the next growing season.