Estimates of monthly and annual mean discharge for five ungaged sites in the lower Columbia River are presented for water years 1928-65. These sites are Columbia River at Vancouver, Wash., Willamette River at mouth, Columbia River at St. Helens, Oreg., Columbia River at Longview, Wash., and Columbia River at mouth. Two tables of estimates are compiled for each site. One table lists estimates of 'observed' flow, the flows that would be measured by a gaging station. The other table lists 'adjusted' flows, the 'observed' flows adjusted for storage changes in major reservoirs arid for diversion at Grand Coulee Dam. Two methods are used in making these estimates. One method involves a detailed summation of flows from all gaged and ungaged areas, allowance for precipitation on and evaporation from the channel water surface, and adjustment of flow to allow for travel time from gaging stations at the Dalles, Oreg. (Columbia River...