Septic Systems & TMDL : How this Rule Impacts Us

In mid-June, the Sonoma County Board of Supervisors took action to meet State mandated septic system regulations that protect water quality and public health.

“Our Local Agency Management Program balances state regulations with local septic policy,” said Board Chair David Rabbitt. “In some areas we are providing more flexibility to homeowners. For example, the new policy no longer requires septic system review for certain building improvements to existing structures.”

Community education and engagement was a central component of the regulation update process. The County hosted six community meetings, met with numerous community associations, welcomed comments in person and online, and provided materials to educate people on the process and technical details.

This has been a VERY long process with community meetings going back decades, yet STILL the problem remains complicated for homeowners from the headwaters of the Russian River, all the way throughout the watershed out to the sea. The estimate is that 18,000 homes will have to comply, so you can see this could take a while!

A central component of Sonoma County’s Local Agency Management Program is the County’s updated Onsite Waste TreatmentSystems (OWTS) Manual. This manual provides the regulations, procedural and technical details governing individual onsite wastewater treatment systems (also referred to as septic systems). The four main changes to local septic requirements relate to:

• Repairs, replacement systems, and new systems;

• Qualified consultants and OWTS designers; and

• Building permit thresholds for septic system review.

The approved changes to the OWTS Manual takes effect July 1, 2019, but it could be another five years before all systems are in place to clean up the problem that impacts water quality along the Russian River and all tributaries leading to the river.

TMDL stands for Total Maximum Daily Load

What that means is how much human waste can the river handle before it becomes toxic for fish, wildlife and humans.

People always bring up that not only human waste ends up in the river, but what they may not know is that human waste is easily differentiated from animal waste, and it’s the human waste that poses the problem.

What’s the major contributor of human waste?

OWTS - Onsite Wastewater Treatment Systems. They are not always SEPTIC systems (a tank that pretreats/decomposes water and waste before the water enters a leach system which disperses the wastewater into soil). They are also often Cesspools (a box that leaches waste into the soil without treatment).

Options to cesspools and septic systems are available...

Sewer systems - complicated and too expensive for small, rural communities).

Aerobic systems - The benefits of this system are that it can be used in homes with smaller lots, inadequate soil conditions, in areas where the water table is too high, or for homes close to a surface water body sensitive to contamination by nutrients contained in wastewater effluent. Regular life-time maintenance should be expected for ATUs.

Mound systems - require a large area of land that cannot be used for anything else. Expensive and not practicle for properties by waterways.

Composting toilets - legal in the state but not legal in Sonoma County.

Is funding available YET?

The county and state are “working on it.” That has been the big wall in front of accomplishing this task of cleaning up our waterways. People who own properties in the area that mandates upgrades can’t always afford replacement systems. Working systems will not need to be replaced, but will be inspected every 5 years. Nonworking systems will be mandated for replacement so the state has a Pilot Project in Monte Rio, one of the communities most impacted by this state mandate.

The project involves finding funding resources for small group systems, as well as for homeowners who can qualify for programs similar to the SCEIP program for on-site energy systems.

Where there’s a will...there’s a way, and even though this has taken decades to get this far, water quality is suffering and that’s one thing everyone can agree on. Getting our rivers clean is essential to all life, to our local economy, and for our fish and wildlife.

For more information regarding the County’s septic policy, including frequently asked questions, and a map to find your property, please visit:

This is also a very useful website to explain different ways wastewater can be treated:

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