San Luis Obispo County has continuously banned applying treated sewage sludge on unincorporated land, and the prohibition was recently extended for three more years.
On Feb. 10, the Board of Supervisors approved stretching an interim moratorium that’s been in place since 2004 until March 31, 2029.
The moratorium extension is a move Atascadero resident David Broadwater supports. But his preference is a permanent ban on applying treated sludge on soil, sprouting from recent community concern that it contains “forever chemicals.”
According to the staff report, there’s a possibility that county staff may present a permanent ordinance later.
“[The staff report] uses passive tense in saying that there is an ‘intent,’ but the report doesn’t say whose intent that is or what kind of ordinance it may be. So, I think the board needs to contact these sewage plants about alternative methods well before that,” Broadwater said. “I’m afraid what they will do is adopt or propose a permissive ordinance that allows [applying treated sludge on land].”
Since the 1990s, Broadwater has been a vocal figure in the area’s discussions on treated sewage sludge, aka biosolids.
The name itself sparks debate.
“That’s public relations terminology that was invented by the nationwide organization that represents the country’s sewage plants in a contest way back in the ’90s for the specific purpose of overcoming public opposition,” Broadwater said, referring to the Water Environment Federation’s 1991 contest to find a more palatable term for sewage sludge. “Biosolids, what the hell is that? I guess I’m a biosolid. You’re a biosolid.”
Local outrage formed in 1998 when waste management subsidiary BioGro applied to the Central Coast Regional Water Quality Control Board to dispose 50,000 tons of treated sewage sludge on a San Miguel alfalfa farm at the confluence of the Estrella and Salinas rivers.
Tension around the presence of heavy metals, pathogens, synthetic chemicals, and pharmaceuticals in that sludge compelled the SLO County Health Commission to consult representatives from the water board, the Farm Bureau, Physicians for Social Responsibility, and Broadwater’s advocacy group, Center for Sludge Information.
The result was a Health Commission recommendation to county supervisors to create a task force that examined whether the county should oversee the land application of treated sewage sludge.
By the end of 1999, the Environmental Health Services Division suggested creating a policy, adding that the issue needed more scrutiny. It concluded that the land application regulations of the U.S. Environmental Protection Agency (EPA), the State Water Resources Control Board, and the Central Coast water board were too lax about the concentrations of the contaminants in treated sewage sludge.
In March 2004, supervisors adopted an ordinance controlling the application of treated sewage sludge or biosolids, periodically extending it every few years.
‘There are an enormous number of chemicals present in biosolids. It’s not just the waste products of humans from eating food. It’s everything that comes out of our bodies and also industrial sources.’
—Peter Hague, SLO County environmental health director
According to the ordinance, wanting to spread 5 cubic yards or more of biosolids requires applying to Environmental Health 30 days in advance.
Only a maximum of 1,500 cubic yards—roughly the load of 12 pickup trucks—of biosolids can be applied over a 12-month period. Applicants must show documentation that the proposed biosolids meet the required “exceptional quality,” or EQ standard as set by the EPA.
Often sold in bagged form at stores and wastewater treatment plants for home gardens and lawns, EQ-level biosolids meet the EPA’s regulations.
Biosolids are the byproduct of wastewater treatment. While treated water can be safely reused, the remaining solids have several possible fates—disposal in landfills or further treatment and reuse as soil amendments or biogas.
SLO County and its cities lack infrastructure that can convert the solid into Class A/EQ biosolids.
County Environmental Health Director Peter Hague told New Times such conversation would require a capital improvement project at wastewater treatment plants. He pointed to the state water board’s one-time assessment of per- and polyfluoroalkyl substances or “forever chemical” PFAS in biosolids.
“Some of the facilities in this county did have PFAS and some did not, and the levels were quite low. But nonetheless, there’s a level of uncertainty,” Hague said. “There are an enormous number of chemicals present in biosolids. It’s not just the waste products of humans from eating food. It’s everything that comes out of our bodies and also industrial sources.”
According to Chris Lehman, SLO’s deputy director overseeing wastewater, SLO contracts with a composter in Santa Maria who blends biosolids from the city and other agencies with green waste to create compost.
“The city of San Luis Obispo anticipates that the production of Class EQ biosolids at the city’s WRRF [Water Resource Recovery Facility], without the need to transport outside of the county, is feasible within the next five to 10 years if a path for land application were identified,” Lehman said.
He added that the cost of trucking away biosolids has increased over the past five years thanks to rising diesel prices.
With an annual volume of biosolids that can top 4,000 tons some years, SLO currently pays a little more than $107 per ton to truck its biosolids to Santa Maria—almost $430,000.
“There are other facilities that transport their biosolids all the way to the Central Valley, where similar operations are performed. A few local agencies transport biosolids to landfills in SLO County,” Lehman said via email. “This option is becoming increasingly difficult following the passage of SB 1383, a state bill that aims to divert organic waste from landfills to reduce greenhouse gas (methane) emissions.”
The overarching issue that regional agencies are trying to solve, he said, is finding the most responsible method of disposing biosolids that doesn’t involve transferring the matter to somewhere else.
Seventeen agencies in SLO and Santa Barbara counties are working together to explore regional solutions for disposing and reusing biosolids.
The city of SLO and the county also use anaerobic digestion to treat and convert biosolids into biogas. A facility that processes biosolids into both soil boosters and biogas could potentially be set up in Paso Robles, according to biosolids and organics management company Lystek’s Solano County General Manager James Dunbar.
“There’s agriculture in that area so we would definitely be willing to invest in a regional-type facility,” he said.
According to Dunbar, while forever chemicals have been around for years and the awareness around them has increased, their potential presence in biosolids isn’t something to be afraid of when private companies like Lystek and public wastewater treatment plants are involved.
“The benefits have been proven over the last many decades,” he said. “In the past, when we would be using lots of chemical fertilizers, those do not have the same benefits to the soil. Given today’s situation with oil and gas and the stresses those are under, we really don’t need to be using fossil fuels to be making fertilizer when we have an alternative.” ∆
Reach Staff Writer Bulbul Rajagopal at brajagopal@newtimesslo.com.
This article appears in April 2-9, 2026.