Marin County is weighing a major change to the way it regulates septic systems. The county’s Community Development Agency is considering an ordinance that would require properties to undergo septic inspections when they change hands, in an effort to gather more records and discourage unpermitted construction. 

The agency’s Environmental Health Services division has no records for 30 percent of the county’s roughly 8,000 septic systems, so it uses building permits as an opportunity to review them. West Marin property owners often dread the septic review that could come with any permit, so many choose to dodge the permitting process altogether. 

“For years, if you get a building permit in unincorporated Marin, you get stuck in the septic revolving door,” said Supervisor Dennis Rodoni, who ran a construction company for 38 years. “Is that the proper mechanism to resolve our lack of data on septic systems? So far it doesn’t work that well because people avoid it by not getting permits to work on things.”

County officials estimate as much as 75 percent of work in unincorporated Marin is done without a building permit, and scrutiny of septic systems is a major driver. The county will often ask for an inspection as a condition for a building permit, even if the project doesn’t make any changes to the septic system. On the county website, septic system permitting guidelines explain that “each building permit application received may potentially require a septic evaluation.” 

Community Development Agency director Tom Lai, who is proposing the resale ordinance, said it would help his agency move away from seemingly random inspections for projects like fences. “The problem with that approach is it creates unnecessary surprises for property owners, and it has the tendency to push work underground,” Mr. Lai said. “They just withdraw the permit application and do it anyway.”

Jessica McIsaac, who runs Pasture Fresh Eggs on the McIsaac dairy, made sure to apply for the necessary permit to build a new loafing barn. The barn will not add to the dairy’s water use or affect its existing wastewater systems, but the county has no septic records for her family’s Tomales dairy, where most of the structures predate regulations, and it used the opportunity to review the systems. 

“My building has no toilet, it has no potable water, yet I couldn’t get the permit without going through a septic review,” Ms. McIsaac said. “There was no reason to bring septic into the situation.”

Mr. Lai cited the McIsaac dairy example as the kind of situation he is looking to prevent in the future. The dairy’s septic systems might be dated, he said, but not necessarily in poor shape. “The new generation has to face the fact that E.H.S. wants to look at their septic system, when they just wanted a new barn,” he said. “I really felt bad for them.”

Mr. Lai hopes to put an end to what he described as “gotcha moments” by moving septic inspections to the time of sale, when he says the extra costs involved won’t be as difficult for property owners to stomach. “At the time of sale, it’s a lot of money on the table,” he said. “It’s going to be less of a surprise.”

Ms. McIsaac said the new system wouldn’t push as many rural property owners to work without permits. “It would benefit rural Marin County to move forward with removing septic review from a permit that doesn’t involve septic,” she said. “It would allow more people to legally obtain permits.”

Ms. McIsaac is not the only West Marin farmer whose building plans have recently been hindered by unexpected septic review. Bivalve Dairy co-owner John Taylor is using funding from multiple sources, including the State Water Resources Control Board, to overhaul the manure management system in an existing barn. 

The dairy currently uses 10,000 gallons of water every day to flush out manure, which then goes into a waste stabilization pond, where it becomes a significant source of greenhouse gas emissions. The dairy’s new project will use barn-cleaning robots to scrape manure into a gutter, where newly built equipment will turn it into compost that can be reapplied to pastures. 

When the county granted Mr. Taylor his permit last year, E.H.S. required an inspection of the farm’s eight septic tanks, five of which are connected to farmworker housing units. Mr. Taylor saw the county’s environmental health concerns as misplaced because of the environmental benefits of the barn project, which he described as a “double win” for carbon sequestration and water usage.

“This project has zero to do with septic,” Mr. Taylor said. “But it gives the county an opportunity to come in and look.”

One of the project’s funders, the Marin Resource Conservation District, helped handle compliance with the septic review, but Mr. Taylor said the work was delayed “pretty significantly.”

Mr. Taylor argued that since his tanks are maintained by the private company City Sewer Service, they shouldn’t require any government review at all. But he said he would support a resale ordinance in place of the current system, with some flexibility for property owners. “We need to have a workaround” for the current system, he said. 

An inspection requirement for every property sale comes with some obvious drawbacks for anyone selling property. Sewer lateral inspections are required by sanitary districts in Marin’s towns, but the county has no such requirement for septic systems, meaning that property sales in unincorporated areas currently come with minimal requirements.

“We’re always cautious about items, requirements, or fees that are added at the point of sale,” said Romeo Arrieta, chief executive officer of the Marin Association of Realtors. He said his group expects to meet with the county to discuss the idea, which he argued could delay sales and cause stress and expenses for buyers. 

Mr. Arrieta also raised doubts about the effectiveness of a resale ordinance. He said the homes that sell may not be the ones with the worst septic problems, so the ordinance wouldn’t be well targeted. He also argued that it could take decades for all the houses in a given area to sell, so the septic information would trickle in slowly.  

But Mr. Lai said a resale ordinance would make the home-buying process more transparent and consumer-friendly, because buyers would know what kind of septic repairs might be necessary in advance. He said buyers could then negotiate the home price with the seller to factor in the repair costs, and work with the county on a “path to compliance.” 

The onus is currently on buyers to do their own research, and people often unknowingly buy properties with failing septic systems, Mr. Lai said. The county recommends prospective buyers hire a registered environmental health specialist or civil engineer to look over the property’s wastewater system, but it doesn’t require such a review. 

Any ordinance would undergo public input and face a vote by the Board of Supervisors, which Supervisor Rodoni said could turn into a rocky process. “Septic is a pretty controversial subject in our rural communities out here,” he said. “I’m not certain that [Mr. Lai] is proposing exactly the right thing.” 

But the supervisor agreed the situation needs to change, and a resale ordinance could be a better alternative than biennial inspections for all properties, a solution proposed by the San Francisco Bay Regional Water Quality Control Board. 

The county is considering the new ordinance as state regulators review its comprehensive plan for new and failing septic systems, the Local Agency Management Program, or LAMP. The program, which has gone back and forth between the state and the county for five years, is the county’s response to Assembly Bill 885, which was signed by Gov. Gray Davis in 2000. The bill and a subsequent regional water quality control board resolution established standards for regulating septic installations, repairs and modifications.

Marin’s LAMP is largely a written description of the county’s existing policies for new septic construction, and it doesn’t concern existing, operational septic systems. But Mr. Lai said it brought renewed focus on those systems from his agency.