The initial stage of Garrison Diversion Unit will divert Missouri River water in North Dakota to irrigate 250,000 acres of land, provide water supplies for municipalities and industries, enhance fish and wildlife, and restore the Devils Lake Chain. Principal areas to be served by the Garrison Diversion Unit are the Souris Section, Central Section, and LaMoure and Oakes Section. Construction of the principal supply works (consisting of Snake Creek Pumping Plant, McClusky Canal and Lonetree I Reservoir) began in 1967 and is scheduled for completion in 1978. Environmental impact statements will be prepared for each of the three areas to be served by the principal supply works prior to initiation of construction in these areas. This study investigates 12 alternative plans, which could be developed in the Souris Section to reduce the effects of return flows on the Souris River. The alternatives investigated are divided into four categories as follows: (A) Reuse of return flows in North Dakota, (B) Dilution of return flows entering the Souris River, (C) Partial development of the Souris Section, and (D) Treatment of return flows, either in North Dakota or Canada.