Stake testing confirms, under natural biological and weathering conditions, the results of laboratory experiments on preservative efficacy. It is required by international authorities for approval of new preservatives. Forintek is the principal source in Canada for the development of performance data on preservatives currently approved for use, and on alternative preservatives which have been identified as potentially useful for the Canadian wood treating industry. Three sites are maintained for this purpose, containing several thousand treated stakes. These are located at Petawawa National Forestry Institute near Chalk River, Ontario; at Forintek's Eastern Laboratory in Ottawa; and at Westham Island, near Vancouver, B.C. This report summarizes preservative performance at Westham Island.