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McMillan Delta Project

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General Description| Plan| Development| Benefits


General Description

The McMillan Delta is a broad, almost flat plain of sediment formed by the Pecos River entrance to McMillan Reservoir. The delta varies in width from 1.5 to 3 miles.

McMillan Dam, in the Carlsbad Project, about 14 miles north of Carlsbad, was constructed in 1893 by private interests and rehabilitated by the Bureau of Reclamation in 1908. Reclamation completed Brantley Dam downstream, breached McMillan Dam, and drained McMillan Reservoir in 1991.

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Salt cedar were first observed in the delta area in 1914, and in the following year about 600 acres of salt cedar were reported. In 1950, the delta area contained about 13,500 acres of salt cedar, tules and marsh grass, salt grass, and trapped lakes.

The plan was advanced by the Pecos River Commission through the joint efforts of the Commission, the Bureau of Reclamation, the New Mexico Interstate Stream Commission, and various other governmental agencies.

Principal features of the Channelization Division consist of a channel heading structure, a water salvage channel, a levee, and a cleared floodway through the delta to the McMillan Reservoir. The second section of the authorizing act included Malaga Bend Division, consisting of the construction of works for the alleviation of salinity in the Pecos River Basin by means of well pumping brine into an evaporation basin. These measures were contemplated to improve the quality and quantity of the inadequate water supply in the Pecos River Basin.

Operating Agencies

The Malaga Bend Division (salinity alleviation works) was operated and maintained by the Red Bluff Water Power Control District from July 1963 to October 1976. Collection of data and evaluation of the effectiveness of the salinity alleviation works was the cooperative responsibility of the U.S. Geological Survey and the Pecos River Commission. Pumping was discontinued when the research purposes of the project were achieved.

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The project was authorized February 20, 1958, by Public Law 85-333 (72 Stat. 17).


Construction of the Malaga Bend Division salinity alleviation works began in 1962 and was completed in 1963. Construction included the enlargement of a U.S. Geological Survey test well drilled in 1939 near the edge of the Pecos River at Malaga Bend, installation of a pump, construction of an 8-inch-diameter disposal pipeline to a natural depression 1.3 miles southeast of the brine well, and compaction of earth materials in the depression to minimize brine seepage losses from the depression. Construction of the Channelization Division water salvage channel, levee, and cleared floodway has not been funded nor initiated. During the 1960`s, the Carlsbad Irrigation District excavated several miles of channel between Lake McMillan and the Artesia bridge. The channel has been effective in minimizing conveyance losses through the delta area.

Last updated: May 27, 2009