Vashon shoreline, aquifer, and county permit lines
Vashon-Maury Island was designated a Sole Source Aquifer by the U.S. Environmental Protection Agency in June 1994, so groundwater is the first constraint we weigh when a drain outlet or infiltration bed is considered. In King County’s Marine Recovery Area, owners must inspect and, when needed, fix or replace their on-site sewage systems, and a septic tank or drain field on a lot can limit where trenches go. We check the parcel’s on-site records before excavation runs close to a house.
Geologists have concluded for some time that most of the island’s shorelines are at risk of landslides, and a 2019 Vashon Beachcomber report quotes a geologist saying failures are most likely on the steepest ground at the shoreline’s edge. King County’s 2026 steep slope guidance treats ground steeper than about 21 degrees, with a vertical change of at least 10 feet, as hazard ground, and work set more than 65 feet back from that ground avoids a geological critical areas report. With no bridge to the island, concrete trucks cross on the Washington State Ferry, so each delivery is booked against the sailing timetable.
Nearby, we also build in Port Orchard, Bremerton, Kingston, and Gig Harbor, and we serve the rest of western Washington.