- This low-elevation wetland and bog complex includes three parallel, elongated basins and their watersheds. Formed by glaciers, the basins are separated by glacial till with no connecting channels, and they support a mosaic of pond, herb and sedge wetlands, sphagnum bog, shrub carr, and second-growth forest buffer. The preserve’s wetland features are exceptional within the Puget Sound lowlands due to their species composition and intact condition. The preserve currently totals 184 acres.