Chemical and Pathgogen Exposure Through Recreational Waters: Physical Processes That Affect Recreational Water Quality

Understanding the physical processes that influence near shore water conditions is critical to beach science and management. Some of the physical processes that influence beaches include the movement of sand and sediment that contribute to beach structure, wave action at the beach and water currents offshore that deliver and wash away contamination, and coastal hydrology, including ground water. USGS provides fundamental Earth Science information on these and other processes, and conducts interdisciplinary studies that integrate physical, biological and chemical conditions and processes at coastal environments.

Current Projects

National Assessment of Shoreline Change. Beach erosion is a chronic problem along most open-ocean shores of the United States. As coastal populations continue to grow, and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present shoreline changes. There is also need for a comprehensive analysis of shoreline movement that is regionally consistent. To meet these national needs, the Coastal and Marine Geology Program of the U.S. Geological Survey (USGS) is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Alaska and Hawaii. A primary goal of this work is to develop standardized methods for mapping and analyzing shoreline movement so that internally consistent updates can periodically be made to record shoreline erosion and accretion.

Submarine ground water discharge. Submarine groundwater discharge has recently been shown to influence bacteria concentrations at California beaches. The USGS has been a leader in developing technologies to study this important process and its affects on nearshore marine environments.

Southern California Sediment Transport and Mapping Projects

Highlights

Bacterial Contamination at Huntington Beach, California--Is It From a Local Offshore Wastewater Outfall? During the summers of 1999 and 2000, beaches at Huntington Beach, California, were repeatedly closed to swimming because of high bacteria levels in the surf zone. The city’s beaches are a major recreational and commercial resource, normally attracting millions of visitors each summer. One possible source of the bacterial contamination was the Orange County Sanitation District’s sewage outfall, which discharges treated wastewater 4.5 miles offshore at a depth of 200 feet. Scientists from the U.S. Geological Survey and cooperating organizations have been investigating whether ocean currents and waves transport the wastewater to the beaches. These studies indicate that bacteria from the outfall are not a significant source of the beach contamination.

Fate and Pathways of Injection-Well Effluent in the Florida Keys Fecal coliform and fecal streptococcal bacteria were associated with three Lower Keys offshore wells and two shallow onshore wells at Key Largo. On occasions, these bacteria were detected farther offshore, once in a well 4 miles off Key Largo. US Geological Survey OFR 94-276.

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U.S. Department of the Interior | U.S. Geological Survey
URL: http://health.usgs.gov/rec_waters/physical_processes.html
Page Contact Information: Herb Buxton
Page Last Modified: 07-Dec-2007@10:29