Legal Framework - 2026
Three things should already have stopped these developments from continuing in their current form - and yet permitting and construction continue.
King County has prohibited LOSSs in Fall City going forward. The County's most recent Comprehensive Plan and code update closed the loophole that allowed these projects to be approved in the first place.
The King County Hearing Examiner has ruled that cumulative environmental impacts must be analyzed before more projects can proceed. The required Environmental Impact Statement has not been prepared.
The LOSS operating model itself does not satisfy state law. No qualifying public-entity third-party guarantor is in place - at Arrington Court today or for any of the proposed Assemblage LOSSs.
These are not theoretical defects. Each of the three is a present-tense, on-the-record finding by an agency or hearing officer with authority over the relevant question. Fall City Sustainable Growth's view is that none of the in-flight Assemblage projects should be moving toward final approval until all three are resolved. We are pushing King County and the Department of Health to apply the rules already on the books.
This page lays out the legal framework in three buckets: land use, environmental protections, and operational compliance so a reader can understand both what is at stake and where the authority lies to fix it.
1. Land Use: We Won the Long Argument. Vesting Is Not a Reason to Keep Building.
When this fight began, the central question was whether Fall City had the protection it was supposed to have under Washington's Growth Management Act (GMA). Fall City sits outside the Urban Growth Area, in a designated Rural Town. The GMA was enacted in 1990 specifically to prevent uncontrolled, infrastructure-deficient growth from consuming rural areas. The framework directs new development into UGAs — which have public sewer, water, and transportation systems — and requires counties to preserve rural character outside those boundaries.
The Fall City Subarea Plan, adopted in 1999 and last amended in 2012, governed how this protection was applied locally. The Subarea Plan was written before the Washington Legislature adopted the Large On-Site Sewage System (LOSS) statute in 2007. As a result, the plan never contemplated residential LOSSs at all — it favored on-site septic and "alternative wastewater disposal systems approved by the Seattle-King County Health Department (such as a community drainfield)." The Department of Health, not the local health department, approves LOSSs. King County's Permitting Division nonetheless treated the Subarea Plan as authority to allow LOSS-served subdivisions in Fall City, importing a category of infrastructure the plan never analyzed and using it to justify density and lot sizes the plan never contemplated.
This has now been corrected. Working in partnership with King County, FCSG helped secure changes to the County's most recent Comprehensive Plan and code update. Going forward:
LOSSs are prohibited for new subdivision projects in the Fall City Rural Town.
Setback requirements have been increased.
These are real, durable wins. They will not be reversed.
The Vesting Question
The County's response on the Assemblage projects already in the pipeline is that those projects are "vested" under the rules in effect when they applied, and therefore the new prohibition does not reach them. FCSG disagrees, and we are pushing this position with King County.
In Washington, the vested rights doctrine protects a developer's right to be evaluated under the zoning and dimensional rules in effect at the time of a complete application. It does not extend to subsequently adopted health, safety, or environmental regulations that respond to risks newly understood by the regulating jurisdiction. The new LOSS prohibition is not a zoning preference. It is a public health and environmental protection adopted because the County determined that LOSSs serving residential subdivisions in Fall City pose unacceptable risk to a sole drinking-water aquifer. A developer cannot vest a right to use a wastewater system the regulating county has now determined is unsafe for the location.
Our view of what should be happening.
King County should apply the new LOSS prohibition to any Assemblage project that has not yet received final plat approval, on the ground that the prohibition is a health and safety regulation rather than a zoning rule subject to vesting. At minimum, the County should pause final plat recording on Cha, Mt. Si, and Cedar 23 until the question is resolved. We are advocating for that outcome directly with the County.
Legal Foundation
Ch. 36.70A RCW — Growth Management Act, including RCW 36.70A.020 (planning goals: reduce sprawl, protect rural character) and RCW 36.70A.070 (rural element)
RCW 58.17.033 — Vesting under the subdivision statute
Washington vested rights doctrine — Limited to zoning and land use rules in effect at the time of complete application; does not extend to public health, environmental, or building safety regulations adopted to address newly recognized risks
King County Comprehensive Plan — adopted under Ch. 36.70A RCW; most recent update Ordinance 19881 (2024)
KCC 20.12.339 — Snoqualmie Valley/Northeast King County Subarea Plan (incorporating the Fall City Subarea Plan)
KCC 13.24.035 — Public sewer service prohibited outside the Urban Growth Area or rural towns specifically approved for sewer (currently only Vashon and Snoqualmie Pass)
Fall City Subarea Plan Policy S-1 — Favors on-site septic and community drainfields approved by the local health department, not LOSSs
Ordinance 19881 (2024) — King County Comprehensive Plan and code update prohibiting LOSSs in Fall City and increasing setbacks
2. Environmental Protections: Cumulative Impact Review Has Not Been Done. Permitting Should Be On Hold Until It Is.
The State Environmental Policy Act (SEPA) requires every state and local agency to evaluate the direct, indirect, and cumulative environmental impacts of proposed development before approval. In a context like Fall City - seven proposed or built subdivisions, in a ½ mile radius, all served by separate LOSSs discharging into the same shallow aquifer - cumulative impact analysis is the central question. The combined effect on groundwater is what matters; the impact of any single LOSS evaluated in isolation is not the right unit of analysis.
King County's Permitting Division did request a cumulative-impact analysis from the developer for transportation only. It did not require one for groundwater, drinking water, the Snoqualmie River, salmon habitat, or rural character. SEPA does not allow that kind of partial review.
On October 7, 2024, the King County Hearing Examiner ruled in FCSG's favor on this issue. The Examiner remanded the Stevens 24 preliminary plat to Permitting and required preparation of a limited-scope Environmental Impact Statement (EIS) analyzing:
Cumulative impacts of all seven LOSSs (Arrington Court, Mt. Si, Cha Cha, Cedar 23, Stevens 24, Fall City II, and Hazel) on the unconfined aquifer, the Snoqualmie River nitrate TMDL, Wetland A/C, and the Barfuse salmon recovery site
The hydraulic connection between the unconfined aquifer and the deeper aquifer that supplies Fall City's drinking water
Cumulative impacts on Fall City Rural Town rural character
That EIS has not been prepared.
What's Actually At Risk
The cumulative-impact review the Examiner ordered is not abstract. It is intended to evaluate concrete, foreseeable harm to multiple protected resources, all of which sit in the same one-mile radius:
The Fall City aquifer. All seven LOSSs sit within a mapped Category II Critical Aquifer Recharge Area (CARA) under King County code. Portions of the Mt. Si and Cha sites also sit within Category I CARA — the most protective designation — and within the 1-year time-of-travel wellhead protection area for Fall City Water District Well 5. Category I CARAs prohibit specified land uses and require enhanced review. Wellhead protection areas exist because contamination introduced inside the 1-year travel zone reaches the well within a year, faster than natural attenuation or remediation can respond.
Fall City's drinking water. The deeper aquifer that supplies Fall City Water District Wells 1, 2, and 5 meets the federal Safe Drinking Water Act's definition of a sole-source aquifer — supplying at least 50% of overlying drinking water with no reasonably available alternative source. EPA has not yet formally designated it as such, but both FCSG's experts and the developer's own hydrogeologist agree it satisfies the federal definition. The King County Hearing Examiner described it as a "de facto sole source aquifer." There is unresolved scientific uncertainty about whether the aquitard separating the shallow and deeper aquifers is continuous beneath Fall City — meaning whether contamination of the shallow aquifer can reach the drinking-water aquifer is not a settled question.
The Snoqualmie River. The shallow aquifer that receives the LOSS discharge flows northwest into the Snoqualmie River alluvium and ultimately into the river itself. The Snoqualmie River is already subject to a state nitrate Total Maximum Daily Load (TMDL) established by the Washington Department of Ecology. Adding seven LOSSs discharging nitrate-laden effluent into the upgradient aquifer — without analysis of how that affects the existing TMDL — is not consistent with the law that established the TMDL in the first place.
Salmon habitat. The Barfuse salmon recovery site lies within the affected area, and Wetland A/C is hydrologically connected to the same groundwater system. Both are protected resources whose impacts the Hearing Examiner specifically required be analyzed.The Procedural Point
Under SEPA, an agency cannot lawfully approve a proposal whose cumulative impacts are part of an unresolved analysis the agency has been ordered to complete. The Examiner's October 2024 remand placed the Stevens 24 preliminary plat in exactly that position — and by extension, the entire Assemblage, since the cumulative-impact set the Examiner identified is the same seven LOSSs across all of the projects. FCSG's view is that no further plat approvals or LOSS operating permits in the Assemblage should issue until the EIS is complete and reviewed.
Our view of what should be happening. Permitting on the remaining Assemblage projects should be suspended until the limited-scope EIS ordered in the Stevens 24 SEPA Decision is completed and reviewed by the Hearing Examiner. Construction at Fall City II — which is currently proceeding — should be paused until the cumulative-impact analysis covers that project as well. We are pushing King County to recognize that the October 2024 remand is not a Stevens 24 problem; it is an Assemblage problem.
Legal Foundation
Ch. 43.21C RCW — State Environmental Policy Act
Ch. 197-11 WAC — SEPA implementing rules
WAC 197-11-060(4)(b) — Lead agency cannot limit consideration of impacts to those within its own jurisdiction
WAC 197-11-080 — Agencies must disclose substantial scientific uncertainty
WAC 197-11-330(3) — Cumulative impacts are part of the significance analysis
WAC 197-11-440(2)(b)(1) and 197-11-960 — Rural character treated as an element of the built environment under SEPA
Stevens 24 SEPA Decision (PLAT220004), King County Hearing Examiner, October 7, 2024 — Remanding the preliminary plat for limited-scope EIS on cumulative impacts of all seven Fall City Assemblage LOSSs
KCC 21A.06.253C, 21A.24.311–316 — Critical Aquifer Recharge Area designations and development standards
WAC 246-290 — Group A Public Water Systems and wellhead protection requirements
Safe Drinking Water Act § 1424(e), 42 U.S.C. § 300h-3(e) — Federal sole source aquifer designation
Snoqualmie River Nitrate TMDL — Washington Department of Ecology
3. Operational Compliance: There Is No Working Model for Operating LOSSs Safely in Fall City. Approvals Should Stop Until There Is One.
A LOSS operating permit is issued on the assumption that the system can be operated lawfully and safely for decades. In Fall City, that assumption has not been demonstrated for a single one of these systems. The only operating LOSS in the Assemblage — Arrington Court — has already failed once. The replacement guarantor structure approved by the Department of Health does not satisfy the public-entity requirement of the LOSS rule. New LOSSs are nonetheless being engineered, approved, and built, with the question of who will actually be accountable for them deferred indefinitely.
How LOSSs Are Supposed to Work
LOSSs are community-scale wastewater systems regulated by the Washington Department of Health under chapter 246-272B WAC. They are technical infrastructure, expensive to maintain, and engineered to discharge treated effluent at specified rates and concentrations into the surrounding groundwater. The regulatory framework recognizes that a homeowners association cannot reliably operate one of these systems on its own over the long term — repairs can be major capital expenses, and homeowners may be unable or unwilling to fund them when the time comes.
The rule therefore requires three roles to be filled at all times:
An owner (typically the developer at first, then the HOA after transfer)
A licensed management entity that performs day-to-day operations and maintenance
A third-party guarantor — a public entity (or, alternatively, a Washington Utilities and Transportation Commission–regulated wastewater company) — that stands behind the system as the ultimate backstop
The third-party guarantor exists because LOSSs that fail can contaminate groundwater, and a non-functional LOSS is not an acceptable outcome. If the HOA cannot or will not fund the necessary repair, the public entity has the statutory authority to assess property fees and execute liens to secure capital quickly, without the delay of civil litigation. That ability — to compel the financial resources needed to fix a failing system — is a functional requirement of the role, not a label.
What's Actually In Place
In Fall City today, the operational structure does not satisfy the rule.
The management entity for the Arrington Court LOSS is Tri County Septic, a private operator. (The same arrangement is proposed for the other Assemblage LOSSs.) Because the management entity is private, the public-entity guarantor requirement is triggered.
The current third-party guarantor for Arrington Court is Kittitas County Sewer District #8 ("K8"), under a contract dated March 6, 2026. DOH approved K8 as the third-party guarantor on March 30, 2026. K8 is also named as the proposed guarantor for Mt. Si, Cha, Cedar 23, Stevens 24, Fall City II, and Hazel.
Based on FCSG's research, K8 does not appear to be a public entity. We cannot find a governing board, a mailing address, posted public meetings, a public records process, or any record of the entity in the Washington Secretary of State's registry. The entity appears in one place: as a named guarantor on Fall City LOSS applications.
If K8 is not a public entity, it does not have the statutory authority or the financial capacity to step in and fix a LOSS that has stopped working. And the public-entity requirement is not only about money. It is about transparency and accountability: public records access, open meetings, elected oversight, and rate accountability that a private entity simply cannot provide. With seven of these systems queued up over Fall City's drinking-water aquifer, that is not a margin of comfort the community can accept.
This Is Not Hypothetical
The exact scenario the public-entity requirement was designed to protect against has already played out at Arrington Court. The Arrington Court LOSS failed in operation, with effluent nitrate well above the permitted limit, and a major retrofit (a community denitrification system) was required to bring it back into compliance. The retrofit happened because Taylor Development still owned the system at the time of failure, had the financial resources to fund the fix, and was motivated to complete it as a precondition to exit. If the HOA had already taken ownership when the failure occurred, the third-party guarantor would have been the entity called upon to step in. The community got lucky once. With six more LOSSs proposed and the deep pocket transitioning out at Arrington Court, the role of the third-party guarantor is no longer hypothetical — it is the next thing the system depends on.
The Path Forward Has Not Been Demonstrated
The most consequential operational question is not whether an individual LOSS can be designed correctly. It is whether a viable, lawful, long-term operating model exists for LOSSs in Fall City. As of 2026, that model has not been demonstrated. No qualifying public entity has stepped forward to accept the third-party guarantor role for the Assemblage LOSSs. The replacement that DOH has approved does not satisfy the rule. And yet additional LOSSs are being engineered, approved, and built — with the operational question deferred to a moment that never quite arrives.
The absence of any qualifying public entity willing to take on these systems is itself a meaningful signal. It is not a regulatory gap that DOH should fill by reinterpreting the rule. It is information about the viability of the underlying model.
Our view of what should be happening. The Department of Health should not approve any additional LOSS operating permits in Fall City until a qualifying public-entity third-party guarantor is in place. King County should not record final plats for Assemblage projects whose LOSSs cannot demonstrate compliance with WAC 246-272B-07000(2)(b). If no qualifying public entity is willing to accept the role, that is a significant signal — and the appropriate response is to acknowledge that the current LOSS development model is not viable for Fall City, not to approve a non-qualifying substitute.
FCSG filed a Petition for Review in Thurston County Superior Court on April 29, 2026, challenging DOH's approval of K8 as a qualifying third-party guarantor. We have also engaged the Consumer Protection Division of the Office of the Attorney General, the Utilities and Transportation Commission, the State Auditor, the State Board of Health, and the applicable legislative delegations.
Legal Foundation
Ch. 70A.115 RCW — Large On-Site Sewage System statute (adopted 2007); RCW 70A.115.005 and 70A.115.020
Ch. 246-272B WAC — DOH LOSS rules; WAC 246-272B-01000 (purpose: sustainable long-term sewage management)
WAC 246-272B-07000(2)(b) — Public-entity (or WUTC-regulated wastewater company) third-party guarantor requirement
WAC 246-272B-02700(4) — Continuous management entity required at all times
WAC 246-272B-04100 — Management entity contract requirements and content
Title 57 RCW — Statutory framework for sewer districts as municipal corporations (assessment authority, public meetings, public records, State Auditor oversight)
Petition for Review filed in Thurston County Superior Court, April 29, 2026 — Fall City Sustainable Growth v. Washington State Department of Health
Where the Authority Lies
The legal framework is in place. Multiple layers of state and county law exist specifically to prevent what is being attempted in Fall City — and on the most consequential issues, the agencies and hearing officers with authority over those questions have already ruled in FCSG's favor or adopted the protections the community has been asking for.
What remains is application. King County's Department of Local Services and the Washington State Department of Health each have the tools they need. The Comprehensive Plan prohibition can be applied to in-flight projects on the ground that public health and environmental protections are not subject to vesting. Permitting can be paused until the cumulative-impact EIS the Hearing Examiner ordered is complete. LOSS operating permits can be withheld until a qualifying public-entity guarantor is actually in place.
Fall City Sustainable Growth's role is to make sure these agencies are held to the standards already in their own rules. That is what the SEPA appeal accomplished. That is what the Comprehensive Plan update accomplished.