In 2006, state law required Puget Sound counties (including King County) to designate MRAs where shellfish growing areas are closed due to bacterial pollution from septic systems, if closure is likely, or where bacteria or nitrogen are seriously affecting water quality. The MRA in King County was established because parts of Vashon-Maury Island were closed for commercial and recreational shellfish harvesting.

During the inspection, a septic system maintainer will find the distribution box, inspect the drainfield by walking over it, look at fixtures and pipe conditions, and any signs of failing. After, an inspection report will be submitted, and homeowners can track their septic system performance in online reports.

Yes, an initial MRA inspection will be more thorough to find information about the septic system if we don't already know that information. The septic system will be located and a dye test completed to check whether all plumbing is connected to the septic system, which makes sure there isn’t surfacing effluent in the drainfield or shoreline. A stress test will also be conducted, which involves running water through the system to see how it flows and if there are any issues. After this initial inspection, on-going routine inspections focus on looking at each component of the system to ensure wastewater is treated properly through the system.

A septic system inspection usually costs $300-400. The OSS Maintenance Rebate Program is available to help with inspection costs. Septic system repairs and replacement costs vary widely. Some fixes are simple and only cost a few hundred dollars. If a new septic system is needed, this usually costs $40,000-50,000. Financial assistance is available for these costs too.

A property owner may request an exemption to MRA inspection requirements if the property meets the following conditions.

• Initial MRA inspection shows that OSS is operating as designed without deficiencies
• Approved OSS record drawing exists
• OSS is over 100 feet from the shoreline

Public Health will evaluate the exemption request to determine if the risk of sewage discharge to the beach is low.

When septic systems don’t fully treat sewage, germs in wastewater flow through the soil on properties and onto the beach. These germs can then get sucked into filter-feeding shellfish or be swallowed by kids who are swimming, causing people to get sick.

Through our work on the VMI shoreline, we have consistently found failing septic systems that cause higher levels of bacteria in the water flowing onto the shoreline.

We use two different tests to help track where bacteria are coming from. We test for bacterial DNA that is only present in the human gut to help us confirm that it is from a human source. Next, we do a dye test in which different colored dyes are added to different septic systems. If a color shows up in the polluted water, it shows us which septic system is contributing to the pollution.

The first step is to know where your septic system is located. You can find your property’s record drawing on the Septic Records Search. Make sure you put only human organics, toilet paper, and a small amount of chemicals or food scraps down the drain. Spread out water usage by doing laundry and running dishwasher at different times. Lastly, learn about local septic resources and opportunities like Vashon Team Septic (Septic Sisters) and the Septic Self-check pilot program.