Sediment Management (Resource Management Strategy)

Sediment in California is a valuable resource when it is properly managed, which results in multiple water benefits, environmental health, economic stability, and coastal safety. Sediment definitions vary among the professional disciplines.

Sediment, as reflected in this resource management strategy report, is composed of natural materials and used contextually as follows:
1. Geology considers sediment to be the solid fragmented material, such as silt, sand, gravel, chemical precipitates, and fossil fragments, which has been transported and deposited by water, ice, or wind, or that accumulates through chemical precipitation or secretion by organisms, and that forms layers on the Earth’s surface. Sedimentary rocks consist of consolidated sediment.
2. The U.S. Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers (USACE) regard sediment as material, such as sand, silt, or clay, suspended in or settled on the bottom of a water body.

Sediments can come from anywhere and be just about anything. Organic and inorganic material alike can become bits of matter tiny enough to be picked up and carried along with a moving fluid. Organic sediments are made up of mostly plant and animal debris. Inorganic sediments are divided into two main groups — coarse-grained sediments and fine-grained sediments. Coarse- grained sediments are boulders, cobbles, gravel, and sand. Fine-grained sediments are silts and clays. Sediment deposits, like tree rings, can serve as a record of natural history.

A further important distinction is whether they are clean sediments or contaminated sediments, as this greatly affects the manner in which they can be used as beneficial material or if they must be isolated from their surrounding environment.