In Yuma County, agriculture depends on the land and on what farmers put into it.
One material used as fertilizer is biosolids, treated human waste that can be applied to agricultural fields under state and federal regulations. Supporters say biosolids return nutrients to the soil and reduce the amount of waste sent to landfills.
But in parts of Yuma County, residents and farmers have raised concerns about flies, odors and the potential health effects on people and animals.
This is the first part of “The Cost of Waste,” a three-part series examining what biosolids are, how they came to Yuma County, what is known about potential health concerns and what solutions may come next.
What are biosolids?
Agriculture professor and program director Hikmet Budak explained how biosolids are used.
“Biosolids are nutrient-rich organic materials,” said Budak, who holds a doctorate in agronomy and horticulture, with a specialization in genetics and genomics.
Budak said biosolids are divided into two classes under federal regulations. Class A biosolids receive treatment intended to significantly reduce pathogens. Class B biosolids receive less extensive treatment and may contain detectable pathogens, according to the U.S. Environmental Protection Agency. Class B materials are subject to additional restrictions on how and where they can be used.
Budak said biosolids are not untreated sewage being spread randomly on fields.
“This is not randomly getting sewage and then putting it randomly into our fields or backyard,” he said. “This is organic material that has important treatment already in place.”
According to the EPA, biosolids are produced during the treatment of wastewater. Solids are separated from the water and processed through methods intended to reduce pathogens and odors before the material is used as fertilizer.
How biosolids came to Yuma County
Lynne Pancrazi, a member of the Yuma County Board of Supervisors representing District 5, was recently appointed to the state Biosolids Committee. The six-member committee was created by the Arizona Legislature to review the use of biosolids, including their application on state trust land and the acceptance of biosolids from other states.
Pancrazi said agricultural interests successfully sought legislation exempting agriculture from many county regulations. As a result, she said, agricultural operations involving biosolids are regulated primarily by state and federal agencies rather than Yuma County.
In 1976, Kenny Evans founded AgTech, a company that pioneered the land application of biosolids in Arizona. In the 1990s, Evans mentored the Magan family in the practice. About a decade ago, the family purchased AgTech.
Pancrazi said AgTech receives biosolids from California, Yuma County and the city of Yuma. The material is applied to leased state trust land, where the company grows crops including alfalfa and Sudan grass. The crops are then sold through a broker.
Pancrazi said an average of 43 truckloads of biosolids enter Yuma County each day. She said the material is classified as Class B and can contain pharmaceuticals and heavy metals, even after treatment.
Concerns about flies
Pancrazi has said the fly problem has affected Orange Grove Elementary School in Somerton, which is located near agricultural operations and waste facilities.
“The flies are so bad that they don’t let them out for recess during that time,” Pancrazi said.
Somerton School District Superintendent Omar Duron replied saying Orange Grove Elementary is not experiencing fly problems and that outdoor activities, including recess, had continued as usual.
“We are aware of reports in the county and are closely monitoring this with the school team as a precaution,” Duron said.
Pancrazi said the county should investigate the seasonal increase in flies, particularly between February and May. She also called for testing of groundwater to determine whether materials applied to fields could be migrating into the aquifer.
“We’re always going to have flies because we are an agricultural industry,” she said. “But the amount of flies that we get from February to May needs to be mitigated.”
AgTech responds
At AgTech, operations manager Kevin Good said the company recognizes that there has been a fly problem in the area but said it has not been linked specifically to the company’s operations.
“There was definitely a fly problem, but it hasn’t been specifically tied to any one thing,” Good said. “I think it’s a little bit of everything.”
Good said AgTech was tested for fly larvae and that no larvae were found.
“We are not a producer of flies,” he said.
A fly test conducted in August 2026 by Yuma County Vector Control found no fly larvae at six inspected locations. The sites included two current application areas, two areas where biosolids had been applied within the previous two weeks, a truck wash-down area and a septic injection site.
Vector Control reported that AgTech cooperated with the inspection.
Chief Health Officer Diana Gomez said Vector Control’s priority is identifying and mitigating public health nuisances that could create unsanitary conditions. She said there was no evidence of disease outbreaks linked to a surge in fly activity caused by AgTech.
Earlier studies
A 2017 analysis by Chris Somner and Elene MacAdan of the Yuma County Pest Abatement District examined fly populations and made recommendations for mitigation.
During the study, traps were placed across one-square-mile sections of Yuma County, extending south of County 19th Street, MacAdan said.
The study found that fly populations were substantially higher south of County 19th Street. On average, researchers recorded 4.1 times more flies in that area than in comparison areas. Some locations recorded fly populations 13.6 times higher, MacAdan said.
The Pest Abatement District later conducted a pathogen study of flies collected near the landfill, biosolids sites, schools, lettuce disposal sites and agricultural fields.
MacAdan said the flies carried foodborne pathogens, including Salmonella and non-O157 Shiga toxin-producing E. coli.
“As they got closer to the biosolids, they were 100% positive for Salmonella,” she said.
Good said the 2016 and 2017 testing was conducted on the eastern side of the farm under a previous leaseholder. He said AgTech took over that portion of the farm in 2020 and cleaned it up under the oversight of the Arizona Department of Environmental Quality.
“ADEQ had the oversight of watching us clean it up,” Good said. “They came regularly and watched that we were doing with fertilizer what was supposed to have been done, which is to put it in the soil, in the fields.”
Regulatory action
ADEQ filed a notice of violation against AgTech on Aug. 19, 2025. The agency closed the notice Jan. 8, 2026, after determining that AgTech met the applicable evidence-of-compliance requirements.
Arizona Attorney General Kris Mayes’ office is testing soil associated with AgTech and investigating the matter. The office is expected to seek answers by December 2026.
Stay tuned for part 2 of The Cost Of Waste… where we’ll be hearing voices from the ground. Tyler Woodman, the man behind the fight to test the soil, workers from AgTech whose livelihood is at risk and public concerns.
