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Enveloping perforated bituminized fiber and plastic subsurface tile drain in a safflower straw sandwich gave excellent performance in maintaining field drainage in Sacramento-San Joaquin Delta tests. A 1-inch glass fiber mat also gave good performance, but tile drains tested without a protecting filter envelope were not successful. The drain failure resulted from sealing by the muck soil, which reduced water movement into the tile—probably a major reason for disappointing experiences with tile in the Delta.