Very fine-grained sand, ranging from 0.0625 to 0.125 mm in diameter (4ø to 3ø), typically doesn’t remain on the exposed (dry) portions of most California beaches due to the high-energy wave environment. An investigation of littoral transport processes and beach sand in northern Monterey Bay (Hicks, 1985), discovered that there is a littoral cut-off diameter, or a grain-size diameter, characteristic of any particular segment of coast. The cut-off diameter serves as a functional grain size boundary in that very little material finer-grained than this diameter actually remains on the exposed beach. The cut-off diameter along any particular beach or stretch of coast is primarily a function of wave energy at that location. Studies along the coast of northern Santa Cruz County, which is a relatively high-energy, exposed coast, determined a littoral cut-off diameter of ~0.18 mm (2.5ø) for this stretch of coast, with very little finer sand remaining on the exposed beaches. In southern California, where much of the coast is protected from strong wave action by the sheltering effect of the Channel Islands, the littoral cut-off diameter is smaller, typically around 0.125mm (3ø). When estimating or calculating inputs to a sand budget or planning a beach nourishment project, it is important to consider the littoral cut-off diameter. Sand placed on the beach or entering a littoral cell that is finer than the littoral cut-off diameter will not remain on the dry beach.