University of California

Subsidence of peat lands of the Sacramento-San Joaquin Delta, California


Walter W. Weir

Author Affiliations

Walter W. Weir was Drainage Engineer, California Agricultural Experiment Station.

Publication Information

Hilgardia 20(3):37-56. DOI:10.3733/hilg.v20n03p037. June 1950.

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At the confluence of the Sacramento and San Joaquin rivers in central California an area of about one quarter million acres, known as the Delta, is made up entirely of peat (fig. 1). These highly organic soils are said to comprise the second largest continuous body of peat land in the United States, exceeded only by the Everglades in Florida.

With minor exceptions, the entire Delta has been reclaimed from tule swamp. In its present high state of cultivation, it produces farm products with an annual value of more than 25 million dollars.

The area consists of a number of tracts and islands, each organized into one or more reclamation districts under state law for the construction, maintenance, and operation of levee and drainage systems. There are more than 80 reclamation districts in this area.

Around the borders of the Delta the peat soils merge gradually into the adjacent mineral soils, or feather out in shallow depths of peat overlying mineral soils. The center of the Delta is composed of islands which are entirely surrounded by the interlacing channels of the two major rivers. In portions of this area the peat is 30 feet or more in depth. All of the channels surrounding the islands are navigable to barges and other freight-carrying craft.

Cultivation in the Delta region dates from the passage of the Swamp and Overflow Act of 1850, when title to these lands passed from the federal government to the state. The first levees were low dikes, truly handmade by Chinese labor with wheelbarrows and shovels. The early reclamation, therefore, did not penetrate deeply into the heart of the peat lands.

Prior to reclamation, the entire area was covered with a dense growth of tule (Scirpus lacustris), with a fringe of willows and other woody plants along the slightly higher stream banks, where the soil contains the greatest amount of mineral material. The surface of the area was at zero, or sea-level, elevation and was inundated at high tide or at flood stage in the rivers.

Partial list of references to papers on subsidence of peat and muck lands

Always F. J. Agricultural value and reclamation of Minnesota peat soils. Minnesota Agr. Exp. Sta. Bul. 1920. 188:

Ayres C. E., Scoates Daniel. Land drainage and reclamation. 1928. McGraw-Hill Book Co. DOI: 10.1097/00010694-194007000-00015 [CrossRef]

Clayton B. S. Subsidence of peat soils in Florida. 1936. U.S.D.A. Bur. Agr. Engin. (Mimeo. report.)

Clayton B. S., Jones L. A. Controlled drainage in the northern Florida Everglades. Agr. Engin. 1941. 22(8):

Dachnowski-Stokes A. P. Factors and problems in the selection of peat lands for different uses. U.S.D.A. Bul. 1926. 1419:

Dachnowski-Stokes A. P. Peat profiles of the Florida Everglades. Washington Acad. Sci. Jour.:. 1930. 20:

Elliott G. R. B., Jones E. R., Zeasman O. R. Pump drainage on the University of Wisconsin marsh. Wisconsin Agr. Exp. Sta. Res. Bul. 1921. 50:

Fowler Gordon. Fenland soils and sub-soils. British Sugar Beet Review. 1947. 16(1):

Gissing Fred T. Peat industry reference book 1920. Moscow, U.S.S.R

McCool M. M., Harmer P. M. Muck soils of Minnesota. Michigan Spec. Bul. 1925. 136:

Okey Chas. W., et al. Subsidence of muck and peat soils of southern Louisiana and Florida. U.S.D.A. Bur. Agr. Engin. 1920. (Mimeo. report.)

Powers W. L. The improvement of marsh lands in western Oregon. Oregon Agr. Exp. Sta. Bul. 1919. p.157.

Powers W. L. Subsidence and durability of peaty soils. Agr. Engin. 1932. 13(3):

Roe H. B. Some soil changes resulting from drainage. Soil Sci. Soc. of Am. Proc. 1939. p.4.

Roe H. B. The soil moisture and cropping problems of peat and muck lands in the northern United States 1943. Michigan Agr. Exp. Sta. Sci. Paper 2032

Weir Walter W. Subsidence of peat land on the Sacramento-San Joaquin Delta of California. 1937. B: Trans. 6th Commission International Society Soil Science

Weir W. 1950. Subsidence of peat lands of the Sacramento-San Joaquin Delta, California. Hilgardia 20(3):37-56. DOI:10.3733/hilg.v20n03p037
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