Wanapum Dam, in the distance, is a hydroelectric project located on the Columbia River downstream (south) from Vantage, Washington where Interstate 90 crosses the Columbia. This is the principal freeway crossing the state of Washington. The area around Vantage has been occupied by the Wanapum Native Americans since prehistory. A number of well-preserved rock-paintings have been found on the cliff walls. They also used the abundant petrified wood in the area for arrowheads and other tools. The site where these petroglyphs were found was inundated by the rising waters behind Wanapum Dam in the 1960s. About 60 of the more than 300 carvings were cut from the basalt cliff face and saved. The site is one of the most unusual fossil forests in the world, and was designated a National Natural Landmark by the National Park Service in 1965.