Insights

Greene Economics led the 2025 update of Thurston County’s On-Site Sewage System Management Plan to meet new state code and strengthen public and environmental health protections for drinking water, shellfish beds, and Puget Sound. The plan targets vulnerable on-site sewage systems—especially in sensitive and flood-prone areas—enhances data and climate change planning, protects sensitive watershed, and supports more than 55,000 systems serving homes and businesses countywide.

Rising ocean temperatures are extending biotoxin closures in Washington shellfish areas. Greene Economics reviewed shellfish fees and recommended state funding for biotoxin testing as a public good to protect public health and support small producers.

Case Study: Greene Economics’ cost analysis helped King County prioritize investments in aging on-site septic systems and equitable infrastructure solutions.