The objective of this study is to determine the cost to society of preserving the Carmanah Creek watershed in its natural state. The cost of preserving the valley is viewed as the cost of forgoing the opportunity to harvest the timber. A complete cost-benefit analysis would compare the economic benefit of logging with the benefit from preserving the timber. Only if the benefits from logging exceed those from preserving should the timber be harvested. But due to the difficulty of measuring intangible non-timber benefits, the cost of the forgone opportunity to harvest the timber is the best measure of the cost of preservation. If the cost of preservation (the benefit of harvesting) is relatively low, then intangible non-timber value are more likely to exceed timber values—the prudent decision would obviously be not to harvest.