During the 1960s, not only timber and ore, but also the water of the western forests as hydroelectric power resources became of interest for commercial profit and national development. A system of several big dams was planned to produce electricity for the growing urban centres. On the Khwae Yai River the Si Nakharin Dam was finished in 1980 and the Tha Thung Na Dam in 1981, while the Khao Laem Dam (renamed Vajiralongkorn Dam) on the Khwae Noi River south of Thung Yai was completed in 1984. The Nam Choan Dam, the last of the projected dams, was supposed to flood a forest area of about 223 km2 within the Thung Yai Naresuan Wildlife Sanctuary.