 Wapato Lake Unit is located about 15 miles ( 24 km ) to the west of the main refuge , near the city of Gaston along Oregon Route 47 in Washington and Yamhill counties . The area was once the site of Wapato Lake , whose soil held an organic @-@ rich peat that sustained a shrub swamp ecosystem . The wapato plant ( Sagittaria fasciculata ) grew in the upper marsh of the Wapato Lake Basin and was harvested by Native Americans . In 1892 , attempts began to drain the 800 acres ( 320 ha ) lake to increase farmland , with the Wapato Improvement District completing the effort in the 1930s . Valley forests , prairies , and wetlands encompass the region today , including two small streams , Ayers and Wapato creeks . 
