Bibliography: p. 57-58 ; Includes graphs, maps ; "Ground-water features of six lowland areas in the Klamath Basin of Oregon--Klamath Marsh area, and Sprague River, Swan Lake, Yonna, Poe, and Langell Valleys--are described in this report. Rugged mountains and ridges surround and separate these lowlands where floors range in altitude from 4,100 feet in Poe Valley to 4,600 feet north of Klamath Marsh. The six areas extend over a north-south distance of 70 miles, an east-west distance of 40 miles, and include an area of approximately 600 square miles... The present level of development of ground water has had no measurable effect on water levels in the aquifers except in three localized areas. In one area, the decline is attributed to uncontrolled flow from artesian wells; in the others, the decline may be due to local pumping from wells. It is concluded that considerably more ground water could be developed safely in most parts of the basin. Aquifers in the main part of Poe Valley and the central and west sides of Langell Valley have little potential as a source of irrigation water, but most other valley areas are potentially productive"--P. 1-2.