Channel Islands National Marine Sanctuary provides habitat for a wealth of biological diversity, outstanding recreational opportunities and spectacular scenery. Every organism that resides within or moves through the sanctuary depends upon clean water, as do all our commercial and recreational uses.
Poor water quality can cause illness or disease, impair condition and reproductive capacity, and decrease productivity in marine organisms. It can also endanger human users of the sanctuary. Sources of water quality impairment in the sanctuary are land-based discharges from the mainland and the islands (e.g., runoff can include sediment, bacteria, and agricultural-based chemicals such as pesticides and herbicides), vessel discharges from recreational, commercial, and industrial vessels (e.g., sewage, bacteria, and marine debris), and discharges associated with oil production (Engle 2006). Nonpoint source pollution from the mainland may reach the eastern portion of the sanctuary (Anacapa and Santa Cruz Islands) during major runoff events via plumes from the Ventura and Santa Clara Rivers (Engle 2006). Agricultural and urban runoff, as well as effluent from municipal wastewater treatment plants, may be some of the sources of pollution from the mainland that reach the sanctuary. Because pollutants can be carried to the sanctuary by ocean currents, or transported through the food chain, the spatial extent of water quality threats is much larger than the sanctuary itself. For example, the pesticide DDT was manufactured in Los Angeles until the early 1970s and discharged into the ocean off the Palos Verdes peninsula. The chemical-contaminated fish within those waters were in turn eaten by seabirds and marine mammals. This affected foraging communities throughout southern California, including the Channel Islands, long after the chemical production stopped. Levels of DDT and a derivative DDE are still measurable in sediments. Some wildlife species such as Bald Eagles are only now beginning to recover.
There are a number of watersheds located on the northern Channel Islands, contributing a small amount of fresh water into the sanctuary. Most fresh water entering the sanctuary region, however, comes from the streams and rivers along the mainland coast, such as the Santa Clara and Ventura Rivers, which provide the majority of the freshwater and sediments into the Santa Barbara Channel. The Santa Ynez and Santa Maria Rivers provide major drainages north of Point Conception. These major rivers have been shown to transport sediment plumes that reach sanctuary waters. The regional coastal mainland also includes the San Antonio Creek watershed and 41 small coastal watersheds on the south side of the Santa Ynez Mountain Range. The creeks of these watersheds provide important nutrients to the marine environment (as well as pollution from agricultural and urban runoff).
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